I only had the PW setup for a week or so, I borrowed it all from a friend to evaluate. I used it with 550EX's so didn't suffer the extreme interference issues so many have with the 580EX II but I found it far from reliable, I couldn't tell you what firmware version it was running but to me it was so inelegant, cludgy and unreliable I never considered buying into the system after using it. It might seem easy and straightforwards to switch things on in a set order, but in the heat of the moment whilst unpacking gear quickly at an event that isn't forefront in my mind, and forget unfamiliar or inexperienced second shooters/assistants , getting misfires and diagnosing and correcting them took too long to sort out too. USB updates, settings via computer, unreliable connections, test firing, etc etc, it just didn't work for me. I hated the need to program in so many preferences via computer too.
The only really cool bit to me was the AC3, now that was so simple and intuitive I wish the guy who designed that part of the system had done the rest of it! That is the only part of the PW system I'd miss to any degree. But the intrinsic limitations of the AC3, the +3/-3 stops over your pre-programmed base point and "only" three groups are negated with the Canon RT system where you have full range control and five groups. There is no doubt as more people use three groups the ones who stand out will be using five more creatively.
The RT system in comparison is fantastic, after really shaking down the PW system and realising it wasn't for me the only other ETTL capable radio system I was interested in was the Phottix Odin. Now that is a really nice piece of kit too, very similar to the Nikon SU800 only radio, very intuitive, good screen angle and excellent feature set that surpasses the Canon feature set, particularly for pre 2012 bodies. But what I wanted, reliability, simplicity, elegance, and most event/reception shooters ideal, one flash on the shoe in ETTL and others doted around to raise the ambient in M, this is one area where the RT system shines, on post 2012 cameras it really is a dream setup and I have used it on 5D MkIII's like that. But I primarily shoot with pre 2012 bodies and although the functionality drops a bit I am still 100% satisfied with my setup. Basically if you have good batteries and turned it on and select slave mode the remotes work. No drama. No special order or test firings. No crossed fingers. It just works.
The range is much greater than Canon suggest too, I don't know why the rating is so low but when I got mine I tested it and was outside firing flashes that were inside my house from 150' away through walls. I haven't noticed a difference in range between the ST-E3-RT and the 600EX-RT as Masters. So my experience with the RT's is that it is 100% reliable at any practical distance I have imagined using. The PW might have a theoretical advantage in range, though many reviews suggest otherwise particularly with the 580EX II, but the RT works every single time at any distance I might need.
So the only real concern you might have is the interface, there is no getting round it, it isn't as fast as the AC3, but it is no slouch and depending on how you use a camera will make flash adjustments work better and faster for some than others. For instance in the above reception scenario I shoot with the camera in M mode with the remotes in M and on camera in ETTL, if I want to lighten or darken the ambient/remotes I just adjust aperture, this doesn't affect the ETTL illuminated subject as they are being metered separately. If I want to adjust the subject exposure I can do that without moving my eye from the viewfinder via the FEC button. So you can have a lot of control without touching the flash setup, I end up with De facto separate control of subject and ambient/remote flashes vie aperture control and FEC all without moving my eye from the viewfinder, don't forget FEC does not affect M flash power, only the ETTL strobes. But other situations can dictate completely different work methods.
If you want to switch off individual Groups then you do need to go into the flash menu but the 600 is so much better than any previous Canon flash for menu controls, indeed it is so good I am happy to play with P:Fn and C:Fn on the fly just for the sake of it. One tiny feature I like that Nikon has had for a long time, adjustable coverage priority, this can be used to nice effect over and above the head zoom function.
Maybe the best thing for you to do would be to either rent some, or buy them from a no quibble return outlet, and give them a real shakedown, but do give the interface a little time, there are so many different ways to work the system I'd be surprised if you couldn't find something that you liked, there is a learning curve but nothing intimidating (and nothing like the PW Flex system), and even after using mine extensively for months I am still finding nuances and applications I hadn't thought of before.
But biggest asset of all? Complete peace of mind in total reliability.
