HK. In your position, I would keep the HK, because it has a recoil reducer built in, and the polymer will allow you to carry it with less fatigue. It's a bit wider, so if you can't conceal it well now, go with the skinnier Kimber. I have a full size USP, and a Kimber Pro Carry(4" bbl.) and for working I would rather have any HK than any 1911. That said, go with what works for you. Have you shot an Ultra Carry? It may or may not be to your liking.
Price wise, this is about even-up. The Kimber is possibly worth a bit more, but not enough that you could actually make money by selling it and buying another USP. Kimber might be worth 50-$75 more at the very most, but go with what you can shoot well. If you're used to the USP, and like it, stick with it.