Still continuing my education on projectors here

Other than the obvious (motorized sceen rolls down with the flick of the switch) are there any other differences in manual and motorized sceens? Is a motorized screen 'stiffer' than a manual screen, making it flatter and less wavy?

Either way this will be a permanent screen so even if it go motorized it will never be rolled up so I could care less about which is easier to pull down/up. If it will never be rolled, is there any reason at all to go motorized? I ask because the place where I'm getting my projector throws in a free manual screen but I can get motorized for a little more. The plan was to paint a screen on the wall but for free I'll give a cheap screen a try