scuff sanding also serves to provide friction while you are brushing and rollingNot sure scuff sand and vacuuming is really that much hand work, maybe couple minutes per window. If there's ever a problem I'd hate to tell them I didn't even bother scuffing.
I've heard good things about that xim bonding primer though, my store has it but I haven't used it. Ever have tannin bleed problems with that stuff or does it seal it?
Why do you use two primer coats on lacquered cabinets? Seems like a lot of extra work