I haven't had the same unreliable connection with my YN-E3-RT as you guys have, but It definitely feels cheaper, and didn't do well when I had it outdoors for a -30C shoot (I can't comment on if the Canon could have fared better).
It works on my 5D2 in the way's I'd want the ST-E3-RT to, and the the AF focus assist is still a nice touch. A friend of mine couldn't get it to work on his Fuji X-Pro1 (remember, this is supposed to offer control with the firmware update on other camera bodies) but again, we haven't tested it beyond that.
I still see it as a workable alternative, but yeah, I wouldn't put everything I had against it, I still pack the Canon one just in case.
Justin, you need to get Firmware version 1.09 for it to work on third party cameras, in the custom functions there becomes an option to turn off the extra hot shoe pins that Canon cameras tell it what is gong on.
FW 1.09 has been in Beta for a while but there seems no widespread recognition of it. Youngnuo are being even quieter than previously.https://dl.dropboxusercontent.com/u/63687922/YN-E3-RT_FW_V1.09beta.zip