I'm 6"1, but only 150 lbs, I have skinny arms and small hands. Smaller than my Dad's who's the same height, but heavier(not saying how much, he might read this.) [:D]
My USP is not too big, it is a USP9F, but I have held the .45 frame, and I would be fine shooting it, it barely bigger.
I was wonder just the same thing today, so I pulled out my Taurus PT92, and my HK, and drew and pointed them. Held them at arms length, saw how the grips felt. They were different, but the USP grip didn't feel or look and bigger. The USP is a bit more boxy than the 92, but that just makes it slimmer, which is good considering how wide the 92 is. Sure the grip is bigger than that of my Kimber, but I still don't see why people say that it is too big...I'm sure it is actually too big for some people, but in that case, many guns will be.
I am on of the biggest HK proponents there are, and I think what some of these people might mean is not "bigger" but different shaped, which it is. I've held a Sig 220, and it felt too big, but I looked at my grip and realized that I had enough wraparound, it just placed and filled my hand differently. Don't get me wrong, if you can't hold it right in YOUR hand, it's not the gun for you, but but considering the guns people pick instead of a "too big" USP, such as Sig 220's, and Beretta 92F's, I think it just felt weird in some people's hands. Give one a chance, go to a range and give one a try.