Yikes. I hope we are wrong....I hope I have mis-interpreted the lack of backwards compatibility. I've based my comments on the description for the AD-E1.
What would this mean for studio strobes? Canon doesn't make studio strobes and if correct, would this make every brand of transmitter for strobes unusable with the R3? One of the reasons I was looking forward to the R3 was the reduced viewfinder lag when shooting with studio strobes.