Be wary of the G400. Despite being the successor of the vaunted MX518, it's made MUCH more cheaply than the MX518 and isn't worth much more than a crappy $15 mouse.
The G500, I've found, is very solid. Feels really well-built and has some heft to it - nothing like the hollow plastic shell mice you find around the $15 mark. That, along with better sensors and more buttons, is the advantage given by a higher-end mouse. It's kinda like driving a BMW after driving a Ford Focus - they'll both get you from point A to point B, but you'll never want to drive that comparatively junky Focus again after driving the BMW.
That analogy is fucking great.
Anyways, The current replacement I've got can certifiably not become my full time mouse, it has a pinky rest and it's making me want to go ape shit.
I've heard some really good things about the G500, I'm not sure though, it flares out at on the right side and the back, and that's the issue I'm having with this current one. Well, the one I'm using on my desktop at least...
A friend of my suggested Steel Series and they look like the kinda mouse I would like but I'm still wary of cords, my computer desk is set up poorly and I'm not sure if it's worth it. I could always plug it into my keyboard but I think the cord would then dangle on my legs and that would make me feel uncomfortable....
I know,I'm fucking weird.
I have another question though, what's the difference between optical and laser?