1. I have not used a Canon 600-RT, so factor that in.
2. I'm not a professional photographer, but do shoot a lot.
3. I have two YN600EX-RTs and the controller. I also have a YN568 (think that is the model) and a YN-RT receiver to use it as a third flash
So far they have worked great. Love being able to do all the controls from either the Yongnuo controller or the built in menus on my 7d2. I only have one gripe and that is the the covers over the ports just don't stay in place. The doors are fine, but the hard rubber covers on the external cable and other ports end up flapping around. Occasionally I find the group number will reset on the flashes. Haven't noticed whether it is the same flash that does it or just a matter of having the batteries out too long. I wouldn't even have gone this route if I had to pay for a Canon flash.