For me, the longer mag levers on the P30 dumps the mag under recoil. Granted, this is a rare issue, but I'm not the only one who has experienced it. This is likely very grip dependent. Also, the USP Compact mags feel less secure than the P2000, but I've never had an issue with the stock mag releases.
I also found the P30 to be very flippy in recoil--uncomfortably so for a 9mm. However, I don't notice this issue with the P2000, which I have found to be the most pleasant and flattest shooting between the P30, USP Compact, and P2000. This is also likely very subjective.
For me and my body type (5'10", 170 lbs, long legs/short torso, pretty straight up and down), the slight increase in grip length between the P30 vs. the P2000 makes a difference in concealment, particularly when carrying AIWB. I prefer guns that are as close to 5.00" in overall height (G19 sized), and of the guns on the market in this size range, I think the P2000 9mm is the best. On the other hand, the P30 seems unnecessarily long in the grip, while being too short in the barrel. The P30L may be a more natural balance, but I don't have any experience with one.
I wish the P2000 backstrap was similar to the 45c--as it is, there is a gap that is noticeable when handling the gun, but not a huge deal during live fire.
I also wish there were more sight options for the P2000. However, the Meprolight factory sights are serviceable, if not great, and the Trijicon "bright and tough" sights are pretty good. I'm not a huge fan of the HD sights, but wish Ameriglo would make the Spartan Tactical sights for the P2000.
The P2000sk has a different shape to the trigger guard than the P2000sk, while the P30sk appears to have the same trigger guard as the P30, so holster compatibility may be better with the P30 guns.
My choice is the P2000, but I think it's a very personal decision, and unless you are one of the few that is affected by the difference in mag release size, it's probably a matter of personal opinion. If you can, try before you buy.