I think using the same mount for everything, if possible, is a good idea. If a mount breaks, you'll nearly always have a spare (even if you have to rob another plane). Your Hayes mount looks pretty sturdy. If the YS fits I would not hesitate to use it.

My brother and I use the Great Planes .40-.70 mount for .61 two strokes and .91 four strokes all the time. We also use it for 40 class two strokes and 70 four strokes.