It would be nice to have a movement block like the SLOW one when you are overweight on flight/hover, since the penalties can be so severe. You may not be slow in normal terms relative to wheels / legs / treads but you are probably much slower than you expect to be. This might be an advanced option.
Yeah that makes sense, (something I haven't encountered as much myself since I don't really use flight :P). I'd say this probably doesn't even need to be an option, just add it as automatic behavior as we already have for the SLOW warning? I can't imagine someone really wanting to turn this off, since at most you'd only want to do this temporarily, and a warning when it once again becomes an issue would be a welcome reminder.
I'll add it for Beta 9.