https://www.ar15.com/forums/armory/Considering-scrapping-the-MPX-platform-and-going-roller-locked-/9-481169/

Honestly the MPX is a better gun all around. And man its easy to clean.

That being said, it depends what you do with it. I think if you buy an MPX and just take it to the range, you will be underwhelmed. Not worth it for that.
I love my MP5 and its fun to shoot, but when I go out really "shooting/hunting" I take the MPX.
The way I view the MPX is almost like another AR. Its boring in way because it just runs so well and easy, but it allows me to shoot 9mm out of an AR but with a better system than a 9mm AR.
I will always have an MP5 and at least one MP5 clone, they are sexy! But the MPX and BCM 11.5" are my real life use guns.  

Read that thread in the HK section.

sounds like these guns suffer the same problem as 9mm AR15s.  Do trigger pins break as often on the Colts with the oversize pins or are they not big enough to make a difference over the standard size.

I'd probably use it for the same reasons you do...............I shoot all of them, and would consider using them for self defense like a PDW type gun if necessary............plus, I like guns.......

I read that thread.............Also read one somewhere else where they talk about clones and the belief that many MP5 clones are not as good as HK guns. Sure, they probably don't have an HK QC man there checking every single one, but after reading posts by Henderson Defense/Battlefield Las Vegas, and talking to them about how the HK clones are holding up to use, I am ok with my Zenith...........but will probably get an MPX for variety

My MPX is bad ass. I'm keeping it.  Don't care if it's a replacement for anything.

More or less this. A lot of SWAT teams are still using the MP5 because they have smaller budgets. Same with regular police forces. As time goes on these will be phased out.

The French just adopted a CZ Bren 806 in 7.62x39 because they wanted a short barreled rifle that could defeat body armor and deliver rifle like performance in a short package. It is a niche weapon and the only bought a tiny number for counter terrorist teams. While the MP7 seems to be loved, I think a lot are not too happy with the damage the smaller round causes to people. So .300 BO and maybe 7.62x39 will take over much of the SMG market, along with 10" 5.56 rifles.

I am sure some will still use a 9mm SMG, but I think the niche is much smaller.

I have a gen 1 MPX SBR, AA94 SBR, Z-5P SBR, SP-10 SBR and a home brew AR9 SBR.

The Sig and AR9 have AR15 familiarity. They are also lighter. They have better accessories compatibility. The Sig is executed very well and is quality...but and this is a big one...Sig screwed all of us that took up the gen 1 platform. Sig switched the platform quickly to gen 2, and has since removed gen 1 caliber conversion kits, which is the beginning of the end of support it seems.

On the HK clone front, I have 3 in 9mm. The Atlantic and Zenith are excellent examples of clones. They are heavier than the AR platform and they are usually more expensive on a parts basis. They also have limited co-wittness optics, but overall, Ill take a rollerlock hk platform any day over the ar platform in 9mm.

With that said this doesnt hold true for .223/.308. I also have two C93 (HK93s), and an V51 SBR (HK91) and a slew of AR15/AR10s. The larger caliber guns are lighter and have better ergonomics in the AR platform over the HK rollerlock.

So in summary. I have and love my MPX, but will never buy another sig product based on the gen 1 experience. But even as such, the MP5 is hands down still the best medium range subgun platform I would go to any time.

Actually everytime we go to the range, im requested to bring one of the 9mm HKs, that has yet to happen for the sig.

You seem ready to throw the baby out with the bath water on Sig over your perception of being slighted.

I have a gen 1 MPX as well I bought the 8” pistol with the folding brace. I run a mix of gen 1 and gen 2 mags. Without issue. I bought probably one of the first 4.5” kits from Sig because it was backordered almost 9 months.

I have literally never had a single failure.

What is so wrong with your gen 1 MPX that you’ll never buy another sig product? I’m geniunely curious because mine has never had an issue, while the quick release of a gen 2 soured me a little, but I never planned on changing from 9mm anyway.

SIG is what's so wrong. Lied about the caliber and upper options. Lied about the ambidextrous charging handle. Lied/changed story repeatedly on the trigger: use any AR trigger! Don't use any other trigger or we'll void your warranty! Well, use any trigger you want but we won't warranty aftermarket triggers!  For me there's the added disappointment of this being my dirtiest 9mm "carbine" by far, despite the supposed benefits of a short-stroke piston system - compared to roller-locked HK clone, various blowbacks.

This is my last SIG product - I won't buy their optics or suppressors either.  Look at the MCX for more evidence of SIG's corporate philosophy of "The customer IS the beta-tester" and their willingness to strand early adopters of "modular platforms" without the modularity they were sold on.  I don't choose to support companies who behave like this.

So there’s nothing technically wrong with your MPX, you just have perceived philosophical differences with the company.  Got it.