It is the 1DX compatibility that I want.
Me too. I now have a 600, a 580exII , an einstein, and 2 B800's that I use 3 flextt5's, a mini, and power MC2 that I can not yet REALLY use.
I have to set the strobes to trigger using the eye on them. inside that is fine but outside it can be tough. my triggers stacked together right now are a $900 paperweight lol.
You *can* use the MiniTT1 on the 5DIII to trigger Einsteins with the PowerMC2. I know because I'm doing it. The only thing is that the AC3 ZoneController won't work if you have it piggybacking on the TT1/TT5 that's on the hotshoe. It was working fine in version 6, but after they released 6.021 beta (and all later releases), it killed the AC3 functionality with the 5DIII.
But it will still do basic triggering.
Although, what I was doing as a workaround if I wanted to use my Einsteins+PowerMC2 with remote power output control, is putting the TT1 on camera, and then placing the AC3 on a FlexTT5 in my pocket. Then I simply did the power adjustment on the AC3+FlexTT5 in hand. Since the TT1+5DIII wasn't sending any power settings even with the in-camera FEC, my AC3+TT5 settings weren't being overridden.
Not optimal, but it works and I can use my 5DIII and not have to fall back on my 5DII.