I have the M95, which is the same basic mouse as the M65, just with more buttons, as it is intended for MMOs, and it is great. It's probably the best mouse I've ever owned, and the aluminum plate on the bottom and solid construction make it feel very sturdy. Definitely go for the black, though, white will show everything that's been on your hand. Also, the white is a glossy plastic that feels uncomfortable if your hand sweats when gaming. Luckily I did get the black one in the first place, as white doesn't match my rig. I'm not sure about the green, as the M95 doesn't come in it so I didn't try it out, but it seems to be the matte/rubberized plastic that the black has.
I replaced my G500 with an M65 a couple of weeks ago. I find I'm unintentionally clicking the right mouse button far less. Other than that, it took a little getting used to the positioning of the DPI adjustment buttons. It's a good, solid mouse.
I have this mouse, used for gaming for months and am currently using it right this second as I type this. Overall i love the mouse, except in the fast paced world of FPS, like TF2 or CS:GO, from my experience, i found myself missing shots, specifically head shots on a fairly consistent basis. Now from what I've gathered online, its about its laser design then optical. I thought at first this experience is psychosomatic, but after switching to the new Logitech Proteus 502 mouse which is optical, i confirmed my suspicions. I read its about the partial acceleration the laser design has, inherent acceleration, that was forcing me to barely miss highly accurate shots. Now i'm sure there is plenty of gamers out there that play a FPS like Bioshock Infinite, where this shouldn't be an issue, but in in a game like TF2 or CS:GO, where this matters, I would prefer optical, and my head shot to body shot ratio has gone far further in favor of head shots when using my optical Logitech.