I have a Logitech G9 and yes its a decent mouse, the G9 was sent to me as a replacement for the G7 which was wireless but also had a design fault that the battery's only lasted a few hours in the end, sometimes only an hour after a full charge so i opted for a nice wired one for replacement as i didnt want that happening again plus being able to weight is nice as i like a heavy mouse.
I only have a few issues...
1. I im unable to reach the "forward" button when i hold the mouse and play games (forward thumb button back one is fine)
2. Wire can sometimes be annoying but 95% of the time its fine and does not bother me.
3. Its a little lighter than the G7 which had perfect weight for me, but then it did have that battery
You can set up custom profiles i think it stores three, i dont know as ive not touched them in years plus i had two that were the same as i sometimes switched during heavy game play. Even though its not as heavy as the G7 its still a decent good weight and as others have said will last for years, ive basically ahd it since the release date (few months after it was released if im honest). I even let my mate use it and he's a Razor fan and he said it was decent but he liked the Mamba so got that. Oh yes the wheel also has two settings super fast (good for long documents) and a slow click. Never liked the razor if im honest think they are over priced and yes i know im prob spelling it wrong im too lazy to check and correct though.
Put weights in your G9 then. They should have come with several.