I love YS engines to death but the 120AX will keep running cost lower for sure. A 120's out put is about the same as the YS110. From my personal experience, there is nothing hard about running a YS but yeah, the 120AX will keep it simple, its just like running a 46 2C for sure.
Mike ... run yer YS! You may fall in love with her. I can't wait to run my YS160 when my plane arrives.