My sister in law gave me her G700S to fix the main button microswitches, and she convinced me that it's the apotheosis of the design - it's what should have replaced the Performance MX. No soft-touch plastic, extra buttons, and the higher resolution sensor. I'll probably have to get one off eBay.
Edit: also all of the Masters have non-user-replaceable batteries.
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.
The G604 that the prior post referenced uses a single AA battery, so also standard and easily replaceable.
(except that my latest one has just suffered catastrophic battery failure)