I have converted 4 of the Stihls and one Redmax 8000....All worked well, about like a G62 for power...The carbs are a pain.....Mounting the Stihl is a bit of a challenge...Mounting using the strongest lugs has the engine running backwards..If you use the other side the lugs are fairly weak, but so far as I know, no one has broken one....
Unless you're a 4 stroke freak a 2 stroke is better, IMHO