I'd like to be able to avoid that jumpy thing that happens when I move models around on the bed. (ctrl-left-drag). I get the idea behind it, but often it's just annoying. sometimes the view changes so much that the model i'm moving is no longer visible. even when that doesn't happen i almost always find it disorienting.
My suggestion is to do a check on the current viewer orientation and if it's close to straight down, then don't do any sudden shift of view. if I go to the trouble to rotate the view so that i'm looking down on the bed (more or less), then you can assume I know what I'm doing and leave the view alone. But (obviously) still only move the model in the xy-plane.
as a first guess, I think that anything within 15 degrees of looking straight down would be a good cutoff.