Yeah, I'll admit that the task-switch button is a little hard to use at times (so much so that I don't bother), but the two auto-cruise buttons aren't too bad. I mainly just use them when I'm reading a long document on the screen, so it's not too bad to just reposition my hand for that task.
The thumb buttons on the MS mice have always just felt awkward to me. I have to really tweak my thumb to get it to hit the buttons, and with the way my knuckles crack and pop know, I didn't think they needed any help.
And I know what you mean about the Logitech drivers and games. It's the one thing that just drives me nuts about it. I did find a workaround, though. You just kill the EM_EXEC process and the problem goes away. Then you just have to restart it when you're done playing. But since I've created two seperate accounts on my PC, one for gaming and one for normal use, it was a piece of cake to just set it up so the Logitech drivers don't run under my gaming account (along with a bunch of other stuff).
I'll definitely be checking out this new MS mouse. I wonder how long it'll be before Logitech releases their own tilt-wheel design...