Ramblings and Canon 600 EX-RT feedback required

Press Correspondent wrote:

The answer to all your flash questions is yes. Canon will recognize 4 or many more units for TTL (TTL2 does do a preflash just before the shot). The specifics you are looking for are in the setup of groups of flashes. I do not have the manual in front of me, but it is the 3rd or 4th group that is considered for the background and could cause an overexposure if pointed at the subject (the experts will correct me if I am way off), but you could assign any number of flashes to the first group or two, so your 4 flash setup is not a problem at all. I just did an indoor wedding with 2 strobes on the camera bracket (600 and 580) plus one off camera for the background. I wish I had two for the background to get it evenly lit from both sides. On camera I planned to bounce the one on top and use a soft box for the one on the left, but the ceiling happened to be black (!) so I had to soft-box both. It was much better than direct flash and the only setup possible without an assistant, but not as good as a completely off camera flash. Are you going to hand hold a camera with 4 strobes on a bracket?!