Shit, Mike, I actually took a look at some youtube videos of these things and I have to say the focus "stepping" lacks smoothness. (What's the point of pulling focus if it looks bad?) Plus I saw one with QC issues.  I did watch a video claiming that Canon USM lenses work great but there wasn't any footage backing it up. :/   I took the plunge on a "remote" follow focus. The problems I encountered were:  1) I can't use a focus-by-wire lens. (Obviously.) 2) I can't use a lens with a loose focusing ring. (Obviously.) 3) My camera needs a cage. 4) My lens mount adapter needs to be mounted to a cheese plate. 5) My camera cage needs to be mounted to that same cheese plate. 6) The #@!$ing lens still wobbles, I need a lens support. 7) The follow focus servo has too much torque. 8) Break down, buy a cine lens, enjoy my new setup and the nirvana of pulling focus remotely.    Anyway, I own this (that's just the remote,) a Wondlan. I wouldn't recommend it to anyone, it's loud, finicky, and I had to swap out servos and solder a new wire to "fix" it.  But now it works beautifully and I'll run it into the ground before I buy something else.