You're making the assumption that braking with your engine causes excessive wear, and I don't think that's true. If you're locking up the wheels through engine braking then you're not doing it properly. youre more likley to wear the clutch when engine braking, than ruin the engine.. if you find youself dragging the clutch as you change down gears, youre doing more harm than good. If you're dragging the clutch when changing down you need to get more rider training, not stop using engine braking.