Or Is it worth getting two separate lower capacity ones and running weapon and drive of separate battery to relieve stress on a single battery?
This is a thing I keep on running into time and time again. The Honey Badger 2.2, Shu! and Kaizen used separate batteries to drive their weapons. However, it does mean more weight and more wiring to deal with but the advantage is that independence which means one system isn't dependant on the battery which drives both. However, in my new Beetleweight and Ikari, they use a single battery for both drive and weapon. Less weight but more risky. Depends on what the design calls for ultimately.