I've plucked a lot of turkeys and chickens as well. Quail skin is frustratingly hard not to tear. I'm sure there are secrets and people that are good at it, though. I think you can get the drill attachment pluckers with smaller fingers that might make it faster and easier.I'm used to plucking chickens so I would guess quail is not hard. The skin adds so much flavor I would hate to remove it.
Here is a video of one with a link: