So after spending a decent amount of time with this set up, I've found two "bugs" that are consistent.
Bug 1 - FlexTT5 does not fire off 430EXII when camera is in Manual Focus & remote trigger. (As soon as I manually press the shutter button it fires off, and as soon as I put it Auto Focus it fires off). But every time I go backto Manual Focus and remote trigger - flash doesn't fire.
^ I can replicate this over and over. Weird Quark, with No Fix.
Bug 2 - (Camera in Av shooting mode)Shooting at high SS like 1/800 and above with AC3 in "A" mode while works fine. But as soon as I put AC3 in "M" to control output manually, I get rear curtain in image (sync issues).
Fix - Put the Camera in M shooting mode and manually select a high shutter speed like 1/800 or above, fire off flash, no curtain/sync issues appear. Then put it back in Av mode and all is well with the world.
^It seems you have to throw the camera into M mode, fire off a high SS shot, then back to Av mode and the bug goes away. I can replicate this over and over again, usually when I first turn everythying on is when the issue happens. The good part about this is I can fix it by putting the camera in M mode, fire flash, then back into Av mode and its fixed (that is till the next time I turn them off and on again).
Weird quarks... perhaps its just with the 5Dmkii ? Not sure... but this is what I've noticed.
I have 2 430EXII's and 2 FlexTT5's. This happens with both.

