I have ordered a little toni and am deciding between these two engines. I have an os 120ax and it has been running fine on my pattern plane, but a friend of mine claims the 91, at least the three he has seen at our field are finicky. Either they are hard to adjust or just don't run that smooth. I know it is only one person's opinion, but the Evo engines at the same field seem to be running good, although I haven't seen the 100 yet. Anyways, I am trying to decide between these two engines. The Evo is ~4oz heavier than the OS ( and $40 cheaper), but at least the muffler isn't the size of a baseball bat
. I can't afford a JETT 91 and have no interest in a ST90, so what's really left other than the OS or EVO? I know a lot of guys are running 91's on the Toni, so I don't think the Evo would be overpowering it that much more, but I am looking at it from more of a reliability standpoint. Comments appreciated.