A quick note on the trigger return spring.
I replace mine every 10k trigger presses, that includes live fire AND dry fire presses.
That spring is flexed with every trigger press, not just during live fire.
Also, the life of the spring is greatly shortened if you put a gouge in it with pliers or a screwdriver when installing it, the gouge is a stress riser and it will break at that weak point.
Either use the H&K armorers pliers designed for TRS installation (or the HKParts.net version) or use the WD-40 nozzle/chopstick trick to install the spring.
Poking and prodding around and scratching things with the wrong tools prematurely kills those springs, I've seen it happen multiple times.
There are a few tricks to quickly, painlessly install the TRS. Learn them and you can swap one out in just a minute or two.
That spring can also be a real pain in the ass if you're doing it wrong, and you will scratch it up doing it the hard way with the wrong tools.

Very smart, I have not heard of anyone else that does this. I can vouch for your replacement schedule as our USP has had two TRS  replacements over the last five years and it is only used for dry fire training. A good habit to encourage if a person is diligent enough.

Went with a USPc40

I have been shooting and carrying a V1 LEM for a couple years and it has been a good pistol.  

Only change has been a set of Trijicon HDs.

I feel the need to revive this thread because of the knowledge in here.

I have put several thousand rounds through my P2000 and would like to keep some spare parts on hand.

What should I buy to keep on hand? I see trigger return springs seem to fail but what else?

Have a few other things I need from hkparts so I wanna get it all at once.

Thanks in advance for all of the good input here.

EXCEPT when someone messed up taking it apart and forces the takedown pin into place... THEN they HATE THEM...

Forcing the take down pin in incorrectly can break the retention tab on the frame, resulting in a trip back to H&K to get a new frame.  buddy is a armorer for CBP and I got to listen to his "I NEED A BEER" story one day after work...

The first P2000 I was exposed to was a CBP issued one.  Half the people hate 'em, but half the people will hate anything you give 'em.

And 90% of the people who love/hate their issued firearm don't have enough knowledge and experience to intelligently defend their love/hate.
It's all feelings and peer pressure mixed with a little anecdotal "evidence" and confirmation bias.
Rarely will you find a true firearms SME who loves/hates a specific duty quality firearm from a major manufacturer, they just make it work.

But mah Glock 9!

I've been looking at a local ad for a P2000 w/ 3 mags for a Glock 19/17. It would be my 17 on the block, were the deal to happen, but I haven't contacted the trader yet. I'm researching the P2000, as I don't know much about HK handguns.

I would trade a Glock for a P2000 LEM in a heartbeat.  I sold my 19s for P2000s and have not regretted it at all.  
The P2000 is, for all intents and purposes, a hammer fired Glock 19.  If it's a DA/SA, the DA is stiff, the SA is decent.

If it's an LEM, then it's a V2 and it's stiff.  A V1 mainspring and firing pin block spring will make it worlds better.

I shoot a Glock 19 faster and better than a P2000.  Slow fire, I can shoot a P2000 better.  

This excerpt from pistol-forum blog talks about why I like the LEM better than I can:

The L.E.M.:
I like the L.E.M. Here is why. It is a consistent trigger. It has all of the take up of the DA, without the weight and effort. The trigger goes back to the same long take up location when the finger comes off the trigger. Essentially, it is like de-cocking without having to use a de-cocker, just a simple removal of the finger from the trigger to its register location. Lots of take up and both tactile feel that the trigger finger is on the trigger, and a visual input from the hammer. That same visual and tactile input is also there during the reset and every other movement of the trigger-you can always see the hammer moving with the trigger.

The negative, is there is a lot of trigger movement going on. This is an issue when pure speed is the goal. It is not an issue when you have to think and justify every single movement of the trigger when employing the gun against people. All that tactile and visual trigger input is a good thing for most people, and gives them a chance to “stop” when something is going on that should not be. I think the best example of what I like about the L.E.M can be summed up with a L.E.M shooting that involved one of my guys.

The officer was working evenings in patrol. He got a call of a domestic disturbance at a 7/11. When he arrived, the male suspect had left walking from the location down a wide main, residential and business, street that intersected the major thoroughfare that the 7/11 was on. The suspect was walking along the sidewalk opposite the flow of traffic carrying a box. The officer drove his marked cruiser up behind the suspect the wrong way in traffic in the #2 lane (closest to the sidewalk) with his window down and attempted to contact the young man. He took off running down the sidewalk and began digging in the box he was holding while the officer pursued in the car.

The officer got the indication that the suspect may be trying to obtain a weapon and began to draw his HK USP45F LEM pistol. The suspect began to withdraw a 6” barreled .357 magnum revolver. The officer (while steering with his knee) drew his pistol, rotated it over and around the steering wheel as a guide (exactly as taught from the ITTS curriculum on vehicle work) so he never crossed his own body, got a two handed grip coming out the window.

The suspect began to turn while still running and leveled the revolver at the officer. The officer planted the sights squarely on the center of the upper body and made a controlled single press of the trigger. The round hit dead center, and the suspect skidded face first into the pavement of the sidewalk “like the rhino in the 300 movie” (exact words of the officer-we had great success with the Federal 230 gr. +P HST).

The officer now had to regain control and stop his vehicle, call for assistance, holster, get out of the car, draw and regain control of the pistol and hold the suspect at gun point with a flashlight until help could arrive, while continuing to provide verbal information using his support hand to operate his radio, then holster again, after securing the suspect.

That is how this stuff happens. How many opportunities to maybe get a finger on the trigger early? Think about having to get a safety off during the draw while making a force decision and driving a vehicle with your knee? Think about having to consciously trying to de-cock or safe the pistol, while regaining control of that vehicle one handed , while you now have to safely holster at speed. Now thinking about exiting that vehicle and starting all over again with the stress and multi-tasking post shooting.

The LEM allows that officer to simply exercise the most basic of putting his finger on the trigger and off the trigger with no other action necessary, and there is some significant leeway built into that trigger for small errors due to distraction or other actions. If we look at the “shooting” part of the above problem, it was fairly simple and a very small portion of the equation, where the mindset and manipulations issues were huge.

I'm torn between a p2000 and a p2000sk AND whether I should go for DA/SA or v1 (light LEM).
If I KNEW my hand would fit on the SK, I'd probably go for it since it would fit between the g19 and the g43/RM380.
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I always felt like the trigger reach was a HAIR too long on the P30 I shot (and a smaller hair long on the VP9 even).  
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While I've read the LEM takes getting used to, it seems fine to me--stage and then fire...in a hurry, just skip the staging.

You're not going to find a V1 P2000, a DA/SA is easy to find, but the DA is atrocious.

Best bet, and what makes the H&K worth having is a V2 LEM, but swap the firing pin block and hammer springs for V1 springs.  It gives you basically a long travel Glock like trigger that is smoother and more consistent.  The V1 just sucks.  I converted a P2000 to V1 and trigger would barely reset.