I haven't shot one yet. However I like to idea of a small pistol caliber carbine.
I thought the 40SW version ran Glock 22 mags, or perhaps I'm mistaken. I have pretty much standardized on 40SW for 95% of my pistols so it makes sense to me to stick with 40SW.
However if there's a kind soul out there who would let me try a Sub2k in either caliber I would certainly appreciate it.
The non Glock models can be easily switched to any other non Glock configuration by switching mag catches ($4.00 ea from KT)
It's said by some owners that the guns with Sig mag catches will also function 100% with CZ75b magazines with no modification.