I've been using the RF-602s for some time now, and I also have a full set of 622s, a 6D, and do the majority of my photography using off-camera flash with remote triggers and shutter. My comments/observations:
I still mostly use my 602s over the 622s. I don't use off-camera eTTL very much, and I prefer the small size of the 602s. Mostly though, I like that the 602s have a 1/4" thread for mounting on stands. They pretty much live on my stands actually - when I use 622s I just put them into the 602s (they're off, just acting as cold shoes).
I do have a couple of issues with the 602s. The off switch is poorly located. They fixed this on the 603 II (but it doesn't have the 1/4" thread). I have to take the flash off to turn access it on the 602 (622s are fine). They also put locks on the hotshoe, something the 602 lacks. Doesn't matter on my receivers since I use the thread, but the transmitter does come loose on occasion. The transmitter also uses a specialized battery (CR2) and the receivers AAA. AAA isn't a big deal, but I like that the 622 uses AA, same as my flashes. The CR2 is a shame, but I shoot a lot of off-camera flash, and the battery last forever. I replace it annually just to be safe. Of, and there's no off-switch on the 602 transmitter, so I have to keep it in a little case that I made (out of a toilet paper roll 8)
I mostly use my little RC1 optical trigger. It's small, easy to use, and doesn't require any additional wires. But it requires line of sight, which can be a little annoying with wide angle lenses with lens hoods. I have an additional RF-602 transmitter that I use with a receiver (and provided wire to connect to shutter release) when I don't want to worry about line of sight, or want to be more than 30 feet away or so. It'll also rapidly trigger the shutter if I want a burst, which the RC1 doesn't do; but that "feature" is as much a hassle as it is a help.
