^^^^ + 1 As Charlie Golf says
Maybe wouldn't look unusual. Don't know the Gnat that well, so it might be unusual as well. Each of the 4 fast jet types I've flown have different ways of inducing roll - one didn't even have ailerons!
LJ
PS. Even a humble Cessna has differential ailerons with 20degs up and 15degs down in full roll control.