I have a G7 and to be honest, it was a tough step for me to take back to a cordless mouse because I'd originally changed a few years ago to an MS IntelliMouse cordless and it sucked badly compared to it's wired brother. I took it back and changed it for a wired. Recently though, I have been using a Razer Diamondback 1600dpi and I loved it, but I decided it was time for a new keyboard so got a Logitech G15 and wanted a mouse to "match" so I took the plunge and ordered myself a G7.
I am extremely impressed with almost every aspect of this mouse, bar one. The lack of a forward button on the side (it only has a back button) but I've managed to work around this now by binding the right movement option of the scroll wheel to forward and that's working fine for me now
The accuracy and speed of this mouse is very impressive. You would honestly never believe it wasn't connected with a wire. It's that fluid and responsive. I have mine on the middle speed setting, but sometimes switch it onto the higher for greater accuracy and speed. This happens fast and it is noticeable right away, so it's really good although takes a little getting used to.
The battery lasts for quite a long while. I play World of Warcraft a lot and I'd say I have to change the battery once every 10 - 12 hours now that it is fully charged and at capacity (I've had the mouse for about a month now). Changing the battery mid-flow isn't a problem either, it's so quick and easy and you don't even have to reinitiate the connection when you put the new battery in. It's already connected as soon as the power activates again. You can turn the mouse off with a button on the bottom too, so you can conserve the power if your PC is on but you're away from it but I don't find it such a problem to be honest.
Anyway, here are my responses to your questions:
1. is there lag? - There is absolutely no lag whatsoever. I've played BF2, WoW, CS:S and Dawn of War and the accuracy, speed and responsiveness is solid throughout
2. how does the battery(s) hold up? - With constant use, well beyond a good 4 - 5 hour gaming session, but most definitely up to 10 - 12 hours (I change the battery once every 2 days)
3. how does it compare to the Habu/copperhead - I've never used a Habu or Copperhead but I had a Diamondback before and I find the G7 a very nice and comfortable mouse to use. The Diamondback was more for left and right handers, whereas the G7 excels at being a nice right-hand mouse
4. are all the buttons capable of being used in older games? - As has already been said, you can bind the buttons to whatever keys or combinations that your keyboard supports so it should definitely work with older games
I hope this helps you out on your quest to buy a new mouse. I was looking for opinions like the ones stated in this thread (except the rather useless initial response) when I was thinking about buying mine, but there weren't any around at all but I'm glad I took the plunge and bought my G7.
