Yep, I'm ceiling mounted. I do have to adjust zoom, shift and focus when switching ARs. As it turns out, most of the movies we've watched so far have been 2.35(ish) but I had to adjust it for a couple yesterday (Death Race and Crank).
Took about 5 mins to shuffle everything around, but I'm not proficient at it yet so it should get faster.
It would be nicer if I only had to adjust the zoom and not bother with shift & focus, but it's not bad.
When I'm banging through pieces of different movies to show off the sub, I don't bother adjusting the AR so it's at least enough work to not make it worthwhile for that sort of shuffling.
Hope that helps.