> But the battery only lasts a day or two
Yes, but the battery is standard and easily replaceable.
My main gripe with the G700s is the weight, although it's not much heavier than the mx master 3. It also helps to have a great mousepad, or else I get tired of pushing that brick around. There are also aftermarket pads if you use it on the desk and they wear. I haven't tried any, though, my pads are still fine.