I personally like my g600 and would replace it with same.

For years I used the logitec mx518, which was great until I played Tera and I needed more mouse buttons because of how I like to play and the way that spells are (were?) ground cast in that game. My first mmo mouse was a razr naga and I HATED it. The size and weight were fine but the buttons are impossible to find without the "temporary training" nubs... that of course then eventually fall off. The subtle tilt to the side buttons on the g600 are vastly superior for making distinctions that become intuitive.

I have small hands (being female) and don't agree that the g600 is too big... but I don't actually use the gshift key, as that would what, require a "grip" to trigger it and a button at the same time, which would feel weird. So that may be why we disagree.

My major hate for the naga comes from how obnoxious I found their software (compared to years of having used logitec for keyboard/mouse and corsair for keyboard). It seemed like every time I opened it it was trying to update its stupid social networking capability or whatever it was. It was also just clunkier than logitec for getting macros/keybinds into it.

My one complaint about the g600 software is that I wish there was a way to make a profile a single profile (for an application) rather than all of them being triples. It is annoying to attempt a keybind and have it fail because it is on one of the other two profiles that I don't use. I get that it is great to have options, but as all of my custom key needs are met by auto switching program profiles, having the manual switch once or twice a day as well is slightly annoying.* I could solve this by duplicating every profile across all three colors but I am not annoyed enough to go through that process.

*Just for clarification this is usually not while gaming, it is almost always when I try to copy paste something and my copy paste keys aren't active.