I maidened a guy's 4*60 with a Saito .91 with an MA 14x6 in it. It performed pretty well, with enough vertical to *just* gain altitude in a hover situation. I'd say any .91 4 stroke will be a good choice with this airframe. It was a docile, predictable, gentle flyer - not really the sort of ship I'd associate with rip snorting "unlimited" vertical performance, at least with its standard wingspan.

Based on this experience, IHMO, fitting a YS 1.10 to this airframe would be a waste of a good powerplant.