It definitely has to do with thier color more than size. I too have black neons with the angels and not one of them has been affected. At one time I had 20 neons in the tank with the angel and one by one they were dissappearing till they were all gone.
FILSTAR Pimp #2
75 gal heavily planted,50/50 Black beauty,Eco-complete substrate, Pressurised CO2 with solenoid, ph controller, AB Reactor 1000, 330 watts 9325K GE PC lighting,Ehiem Liquidoser, 2-Filstar xp3 canisters.