I had a set of the R685 on my CX bike which are prototypes. They never sent me any rotors so I ran SLX rotors with them, but I took them off after a month and went back to CX77 mechanicals. They were very powerful but difficult to modulate, for example, if I was dismounting for a hurdle, and was stood on one pedal, I had a couple of moments where I nearly went over the bars, because the brakes were either on or off, and on bumpy ground it was quite difficult to avoid the bike stopping dead and throwing you forward. The levers which admittedly look very compact compared to Sram’s offering, still felt very big compared to the new 11 speed 105 offerings which feel nice and compact. The hoods felt quite baggy too and weren’t a great fit around the lever but they might be improved for the production ones. I wouldn’t say they were rubbish, the power is certainly there, the production ones might be better but I think there’s a bit of a wait for them.