I have demoed US k90 again this weekend and as a proud owner of Asian k90 I am having an itch to buy US version as well as I found it to be little bit more stable on slice returns and sometimes on serve (I will explain why sometimes) Volleys:More heft in US k90 felt more stable on the volleys I am not S&W player but I do find myself "OUT THERE" every now and then to finish up the point. Groundies:Felt great, stable and little taxing on your arm if you are not use to the weight. I found myself slicing more than usual but I am not sure if that was due to the fact that added weight made me a little lazy, or I felt more secure in slicing, since slicing with US k90 was F**K**G sweet. Serve: I found that US k90 CAN serve better if you let the racquet do the work for you and you have very relaxed arm. If you are type of server who muscles the ball you might like Asian k90 better as it is much lighter this easier to muscle around. Return of serve:US 90 wind this one as added heft again helps out returning heavy serve. Slice return, block return all were great. My timing was little off with US k90 on swinging returns as I as use to the more maneuverable AK90. I am little torn I love specific char. of both and i seems to me that baseliners would love Asian k90 better while US k90 would be more for S&W types. Have others who own both versions had similar experience?