Viddovation
Veteran
We are trying to get the OptiTron compatible with Canon cameras as well. But you are absolutely right.
F5 (F3 as well) with the OptiTron2 and the Canon ProLock Mark1-2-3 is the only combo with EFF (electronic follow focus)
For now:
http://optitek.org/products/optitron2/
check out the videos on the bottom of the page ;-)
And to be clear, I definitely don't mean to malign the Optitron products - they look very cool, and I only hear good things. But the special features they offer aren't something that casual EF shooters can necessarily justify when other options give them an entire camera with basic EF electronic control for just $500 or $750 more.