I find it funny that my $14 Logitech MX300 lets me own the n00bs with $80 mice. =D
Not that some of them don't own me... But I know in those cases that it's not the mice.
My friend upgraded to a Razer Diamondback and it ruined his CS 1.6 game. He says it's way too sensitive even on the lowest. I think he also played with 1.0 sensitivity before that... So take it with a grain of salt.