i would have went with the saito 100 but didnt have the opportunity before the YS 110 came up. the saito is actually cheaper. but not to be argumentative but the box said one engine range and the website had another: Engine Size:.60–.75 2-stroke; .91–1.00 4-stroke

the YS is not so much heavier that it will be that much of a problem plus has more power than the 100. however this airplane if you look in the arf forums isnt good for 3D because of undersized ailerons. if it were me and i had the money to spend on a new engine i would go with the saito just because if you have no experience with YS's they are bit hard to get tuned right because the fuel system is problematic if everything isnt working 100 percent. I will probably fly more pattern with mine until i can build my ultrasport 60. or I may end up buying an aeroworks 60-90 size for 3D. I got my Seagull airframe for free at a swap meet.