Logitech did a pretty quick turnarond on replacing my G7 mouse (12 days with the holiday). My replacement G7 mouse broke after about a year (I got the first one in Nov. 2008 I think). I was never really that happy with it. Worked well enough, but swapping out the battery pack (which does take a few seconds) seemingly every other day was annoying. Paled in comparison to the MX10000 I had. That thing rocked.
The G7 is discontinued so Logitech sent me a G700 ($100 MSRP). I think I have the sensitivity the way I like now and you can customize the buttons for macros and stuff (it also holds 5 different profile settings). I probably won’t mess with the customization. It is REALLY comfortable in the hand. It fits perfectly and it moves around the desk surface really well. There is a rechargeable AA in there, the recharge cable doubles as the data cable, so it turns into a wired mouse when you plug it in. The charger fits flush into the top, you’d never know it was a wireless mouse looking at it. I got the mouse yesterday so I have no idea what the battery life is like yet.