I do not own a YS but I do own an OS 70 Surpass. It is totally reliable and easy to run. I followed the OS instructions for break in and use a 13x6 prop. There are pilots in my club who run YS and they do not have problems with them either, but they do run YS 20/20 fuel or 30% helicopter fuel.

Saito engines could be another good option if they are available to you at a reasonable price. The Saito manual does recommend 10 to 15% nitro so I do not know if they would run well for you.