Hi there, Steve. . .
We don't have even the tiniest issue with pulling focus with or Canon glass, and we do HUGE pulls all the time. . . I mean, really massive pulls in some cases (say from 20 feet to 1 foot at f1.2), and whereas we miss these pulls a lot of time (due to insufficient marks or just plain old operator error), we NEVER have had an issue with not being able to pull perfect focus when we've got accurate marks and are actually paying attention. This thing just never drifts.
I know they aren't for everyone, but the Canon glass has served us so well and faithfully it's amazing. We used Nikon glass before that, but that glass didn't allow a remote focus puller. With the Birger, that's no issue at all.
I agree, Roberto. . . I like your style. . . I just haven't found the need, to this point, to even covet that great PL glass. Sure my pups breathe a little more than some PL glass, but I actually like breathing under certain circumstances.
I WOULD love to be able to do a smooth iris change, but that doesn't happen very often in our shooting.