TJ Helmerich is a master of 8-finger tapping, and it is primarily all he does, at least in a lead context. His left hand (the normal fretting hand) is used primarily to support, extend lines, and create wide intervals, while he does most of the scalar legato things, which most people would do with their left hand, with his right. He does all his vibrato and bending with his left hand though, so it has that particular sound you get when you bend a tap from behind. Helmerich's technique is miles beyond what Watson was exploring.
Check out the album Quid Pro Quo by
Brett Garsed and TJ Helmerich if you are really interested in it. Plus its worth getting just to listen to Garsed.