I've got the Faco front rack, and it works just fine. I don't use it a whole lot, but I know from previous experience that it's worth having one.
I currently have it off because I'm pissed at it.
Even though I put small pieces of plastic (OK, so they were circular cut-outs from a freezer Ziplock baggie) behind the rubber support cups, those damn things still marred the paint on my legshield. It isn't bad enough to bother using touch-up, and wouldn't look right if I did, but it's enough to see in daylight, and it really bothers me. I keep my scooter pretty clean, so the ivory will definately show if there's damage to it. The damage is pretty much the take-it-to-a-shop variety if I wanted it to be perfect again, but I really don't want to do that until there's issues all over the bike (which, I'm hoping, won't be for a decade or so).
I would kind of like a smaller front rack anyway, as I don't like to carry large loads on the front. The rack I had on a previous scooter was jerry-rigged from an old Vespa smallframe's rear rack, so I'm used to the smaller size on the front. I know this may be kind of a tough question without visually "testing" every kind of rack... but do most of the front racks have their rubber support cups in the same place? If I get a smaller rack, it will likely be the type that needs to actually be bolted on under the Piaggio badge, so I probably won't take it off except a few times a year to clean under the cups. But it'd be nice if the cups would cover, or at least line up with, the damage that's already been done.
Yeah, I'm stupidly picky about my paintjob. My cheap-ass Chinese bicycle has been through a lot more hell, and its paint has held up better than my expensive Italian scooter.