I get around 6 full race meetings out of that setup on average, but it is only because the muge shoes will wear out. The Alloy one stays on for about 20 races. The benfit is that the alloy shoe also scrapes off the residue from the whites and so the bell remains cleaner and lasts longer.

BTW the mugen shoes I use are on a Hyper flywheel, on an XB8. It does hang down 1mm below the chassis but has never been shaged enough to cut the engine.