lock_ wrote: Few catalogue pictures of the 6870 Ultegra Di2 and the hydro disc brake rotor, pad and calliper.
Calliper gets the designation of BR-R785, according to my understanding this puts it at an Ultegra type level. This is fine by me, hate to think what price a DA Hydraulic Di2 groupset would go for. The hydraulic stuff doesn't seem branded to any spec level (eg; Ultegra or DA), guess they didn't want people to shy away from mix 'n matching.
Historically, the R700-series designation has been applied to "non groupset" Dura Ace level components (hinted at by until now Dura Ace having a 7000-series designation), R600 has been Ultegra equivalent (harking back to when that second tier group was called 600), etc.
However, in this case it would appear that the historical pattern is being passed over in favour of aligning the brakes with the XT mountain M785 & "trekking" (hybrid/touring-type setup) T785 series, which are basically the off-road equvalent of Ultegra anyway.