I've bought and sold basses through them & become good friends with Phil the owner.
The big advantage for me in selling basses via BassGear is that Phil has quite a few overseas customers & he handles all the international payment & shipping stuff. I think some of my basses have gone to France, Austria, Scandinavia etc.
They moved location a few months back & now just 20 minutes from my house which is brilliant - I can't keep away from the place, lol.
The new location is right next to Twyford mainline station too if you want to get there by train