I happen to have run both the YS110S and the Saito 125 on that very same aircraft.
Each was run on 30% Wildcat, all synthetic. The mounting holes and mounting hole to back of prop dimension are identical. Only the servo/throttle linkage needs to change sides. With mufflers in place (stock) they are the same weight

Power = no contest. The YS was consistently 1000 rpm better on a 15x8 APC. The YS when flown a little will go to a 15x10. The Saito stops at the 15x8. The 15x10 is too much for it.

Tuning, well that is a no contest also.
The Saito sets up very quickly.
The YS is a royal PITA to set up but once you do get it right it has power to spare.
I had each engine mounted on the same Hyde mount with different cowls cut out to match the engine.

If you want to do the Focus Sport justice in the air, it has to be the YS.
I've since gone all electric but that was my last Glow set up.

BTW, I have not exaggerated one bit !
Not on the set up !! - and not on the power either.

Unless you want aerobatic limitations (the 125 will give unlimited vertical but does NOT begin to have the authority of the YS.) you should either find an available YS110S or simply wait for even more power and the 115.
Hopefully the new regulator set up on the 115 will make set up easier. Trust me, that will not be hard to do. []

I'd wait for the 115 (same mounting dimensions as the 110) but it is your choice.