It sounds a little bit small...................I have the MS170. It's the smallest Stihl that I've used and I'm not overly impressed with it's power. I was having a bit of an issue with it bogging down the first year too... until I realized it REALLY liked a clean air filter. Once I changed that out on a more regular basis and always had a spare or two it worked better. It is still the smallest saw I've ever used and I just have to be patient using it I guess.
No problems with it.... because it's a Stihl of course ;)