My Kimber Ultra Carry is dead solid reliable. Not even picky about mags.
I can even load up standard size mags and they work fine. (just poke out the bottom)
The issue I had with the factory Kimber mags on my gun was the followers were wearing a groove into the feed ramp on the aluminum frame. I switched the Kimber followers for Wilson plastic followers and also used Wilson mags. This stopped the wear, but didnt do anything for helping function.
As for springs, if you you go through Kimber, it will cost you a good bit more, but they come as a unit with the guide rod. I think it was around $45 at the time for the set. Wolf has replacement spring sets for a lot cheaper, I think it was $5-6, but you do need to swap them off the original guide rod yourself. Not hard, but not always fun.
I always used to carry basically stock Commanders and occasionally a GM, and never had any issues with them. The 1911's I always had troubles with, were the ones that wandered from the basic Colt/GI specs, and especially those that differed in slide, frame, and barrel dimensions. I never had good luck with FLGR's either, even in the full sized guns.
If you got a short one that works, I kind of envy you, as I always wanted my Ultra Carry to work. If your looking at buying one of the smaller guns, I'd highly suggest you try one out, before you by. It will also give you an idea of how they handle, as they do handle somewhat different than the GM/Commanders.
It would be better to shoot someone elses gun that has been shot in awhile too, that way there are no "break in" issues that seem to be the norm these days with a lot of the 1911's and you can see if there might be issues due to springs getting weak.