I was just at a lan party last week, about 18 people there, and there were over 10 MS intellimouse opticals. There was 1 Logitech, the highest end version. I thought they both felt the same movement and smoothness wise. The Logitech may be better ergonamically for some, but not for others, and I pretty much can get used to any mouse I have. MS seems more cheaply built, but they are heavily warrantied, so that wasn't even a thought for me. The 1 difference I really saw between the 2 was that the Logitech would skip around when lifted up to center on the mousepad, while the MS would not. This can be deadly in games, which is what I will use it for. I'm pretty sure I'm going to be getting the MS in the end. Hope this helps.