Can't decide whether to go with the .40S&W or the 9mm.  Looks like only 1rnd difference in terms of capacity.  Your thoughts?

If you can place both where you need to, bigger is ALWAYS better with DEFENSIVE loads, especially if the cost is only one round.

Whichever one you shoot better with. If cost is a concern, you can practice a lot more with 9mm since it's so cheap.

I agree, I could probably get a lot more practice with the 9mm.  Also, I'm somewhat concerned about the recoil of the .40S&W seeing as it's such a small pistol.  I want to be able to place a quick & accurate follow up shot.

Comparing pistol rounds these days is mental masturbation unless you plan to use FMJ. The performance difference between similar loads in 9mm and .40  is 3% or less. So whichever one you shoot best.

I shoot the XD40 .40

Groups very well, good recoil control.  100% better with a pinky extension, absolute must

Quoted:
Comparing pistol rounds these days is mental masturbation unless you plan to use FMJ. The performance difference between similar loads in 9mm and .40  is 3% or less. So whichever one you shoot best.

So true, I love to shoot my 45 but a carry a 9MM. I can place 2nd and 3rd shots a lot faster.

Up to you on caliber.  I love my XD9 SC and carry it quite a bit.  I use a CTAC holster that allows for your shirt to be tucked over it.  Great at work with casual dress or going on somewhere where you should have your shirt tucked it.  Harder to get to, but with practice it can be drawn pretty quickly.

The XD is a reliable pistol and easy to handle.  Its combat accurate and does its job rather well.

I took a XD9 service through a pistol course where I was dropping magazines on the ground and firing hundreds of rounds through the pistol.  It never flinched once and the magazines fed properly even when filled with sand and dirt.  

I odn't have the pinky extension on my magazines but have shot it with some and I agree it helps.  I do alright without them and just never spent the money on getting them.

I really like the XD and recommend it to a lot of people who don't like the Glock grip angle and what a reliable and lightweight pistol.

i would go with the 9mm purely for recoil - the .40 is snappy out of full size guns, i wouldnt want to shoot it out of a subcompact - i would think it would be like shooting my airweight .38 snubby. not an enjoyable gun to shoot.

get the XD9

my .02

I love my XD9 subcompact and would also recommend it for CCW.  I have never shot a pistol that felt so natural.  I have a CTAC for mine but I want to get a VMII soon.