Very disappointed I am about the fact that there is still no firmware update that the EOS 6D and EOS 1DX fully supported (see Update). Manual triggering works, but no TTL, but that's why you pay precisely the charge for the FlexTT5 to other Pocket Wizards.
The Pocket Wizards are often praised as particularly reliable in contrast to other systems. I think that's an exaggeration. With cheap transmitters as the Youngnuo RF 602 which, although no TTL can I previously had significantly fewer problems. This is certainly the fact that the system is much simpler. However, it also paid a corresponding chunk of money for the Pocket Wizards.
Update: Meanwhile PocketWizard has (finally) delivered a firmware update that supports 6D and 1D X.