I had the same question about one month ago (since 303 is formulated for plastics/vinyl/etc, wouldn't it be "best" for urethane clear bras).
So far, I've put Zaino on both the clear bra and the paint. I think for the parts where the clear bra and paint meet (hood/fenders), there may be an advantage to use the same product on both to try and keep the two parts looking as close as possible.
I also have the clear bra applied to the front bumper (G35). I am thinking of trying 303 Aerospace on the front bumper clear bra next time, since the front bumper is a separate piece, so I would not be as concerned about using the same product there.