DON'T get the Troy-Bilt version. I had the 2 cycle model from about 10 years ago. Very weak, poorly sealed worm drive tranny. Mine froze after about 50 hours. TB would not warranty it beacuse they said it wasn't maintained. (which is bs, but you are at the mercy of the mechanic's opinion of the failure)
The ECHO (Mantis) is much more durable. I would like to try the Stihl unit, though.