I've had my US-KOC since the beginning, and not had a single problem with it, other than tight TT which I modded and works perfectly now.
I actually like the increased strength needed to hit the keys, I've gotten many, many new AAA's, AA's and FCs with it than I did with the JP-KOC. :3
That, and I believe it was said that the key's depth of sinking is around the same as the actual Sanwa keys in AC IIDX.
