Would this combo work, and would it offer any advantage other than tool free adjustment?
I’ve got a set of both at my disposal, and have to take the 6120s apart to put them through the frame, so if there’s any benefit then I may as well swap levers.
Both use BH90 hose.

Am I right in thinking it should give a bit more power, as the 675 levers have the variable cam thing and the 6100s don’t?

Not so I’ve noticed … I’ve got various mixes of 675/785/7000/8000 calipers including one bike with a M6000 lever on one side and Zee on the other (to some SLX or XT caliper couldn’t say which without looking). I’ve also got some 7000 levers on 7120 calipers… about the only one I notice any real difference not down to the pads.

Hmm, interesting. I was sure if heard that the swing link thing wasn’t on the Deores. Maybe that’s my Guide R/RS brain getting confused!

Edit: just looked at the Shimano page where it clearly states it has servo wave. So I guess it’s just tool free adjustment and lever shape 🙂