Yep on all those fronts.
I have to agree with Illya here. The real issue itself is the EF mount (the on lens and camera mount) is not designed for motion use. It was designed for the lightest and quickest way to attach a lens to still camera. There's been a few advancements like the locking/tightening collar on the Red DSMC Canon Mount for instance, which helps. But give a lens a firm handshake and you see that wiggle. I shoot with Canon and PL glass. I've got over 40 EF lenses. It's there.
Is it unusable? Hell no. I use them all the time. But there's zero chance the EF mount concept is as sturdy as a traditional PL mount. That comes down to the materials used and the overall design.
I see it the most using electronic and mechanical follow focus units. The less friction the lens focus ring has the less noticeable it is. But, with EF glass you're often combating a combination of things that don't play super nice together when working in motion. That's just what it is.
The mounts in general are real sturdy on the Xenon FF-Primes:
However, the final production mount is a bit different than the picture above. Still rock solid though, which is good.
You don't ever want to do it, but a good solid mount is a mount you feel like you can lift the camera from the lens without ripping the mount off the lens or body. Again, don't try that though.
