better sensors are better
the shell is just taste
'better' mice though are usually about a feature set... like more buttons, dpi changing, etc. the g9's scroll wheel can be set to scroll with or without clicking. it's great on free-roll mode... so fun.
a better mouse is better, yes
especially if you are on a keyboard forum
with hundreds of dollars' worth in your sig
get an MX518 off ebay or something (id sell you mine if it was still here), a good place to start
EDIT then there's the whole aftermarket feet / premium pad game... which makes much more difference than you might think. i wouldnt go as far to rip off brand new feet in favor of hyperglides, but i definitely now know what to get when they wear out. they aren't THAT expensive, so it makes using a "rough mousepad that RUINS YOUR MICE!" more like a very cheap ($15 a year?) preference.