Definitely interested to here how they go man.
The Yongnuos showed up yesterday, pretty quick postage from the ebay seller.
First impression: fuck, these things are big! Like big big. "I'm gonna need to actually consider them when I pack my bag, and I don't know if I'd take them travelling unless I had good reason" big. Not a deal breaker or anything, but worth considering if space in your bag is at a premium.
Second impression: they don't seem terribly useful with EX (non-II) flashes. Even with the 40D, which has a flash control menu, I don't seem to be getting ETTL or HSS functions. Gonna play some more now, will report back.
Edit: Mmmkay, now I'm really fucking confused. I moved the setup from one camera to another, and I got ttl and hss working. Then I put it back on the 5d and it seemed to work there as well. I switched the triggers around and now I don't seem to have ttl working. I am getting HSS working right up to 1/8000th though, which is pretty impressive, even though I couldn't get anything above 1/250th initially.
So the only thing I know right now is that there's 'limited' functionality with EX series flashes.
Edit II: I did a reset on the triggers and reset the sppedlight too, and now I seem to have ETTL operating just as expected, as well as HSS up to 1/8000th. No remote control of flash settings with the gear I have at the moment and only newer gen flashes will give that control. I did get a moment of weird behaviour once after the flash went to sleep, and didn't seem to want to be woken by the camera, but that just seems to be a one off.
I found
this guide that someone has put together too, and it seems pretty damn good. Worth a read if you're keen on these.
If they keep behaving themselves now I think I'll be very happy with them. No sensor interference, remote ETTL (with on cam FEC) and good HSS at this price is pretty damn hard to beat. If you have EXII flashes and want to shoot with manual levels, I'd probably buy the King Pros, purely for the direct controls on the back of the trigger; canons on-cam menu is a bit of a shit to navigate through, at least the version on my 40D is; if I had to use that all the time I'd probably just start walking around to the flashes.
If anyone wants specific things checked, let me know, just bear in mind I haven't got any EXII speedlights. I'll probably order another set of triggers though so I can play with multiple lights and see how ratio control works with the on-cam menu of the 40D.