I've got the homeowner models. Two of the KM55 heads, two polesaws, one extension pole, one string trimmer, one blade attachment for the trimmer, one blower.
Never had any issues.
Granted, I do not use them in a commercial application.
On the other hand I have six (6) acres of lawn, and 44-acres total on my farm. Most of which had not been touched since 1989, and I took possession of my farm in 2010. Overgrown does not quite describe it.
I have been beating on my Kombi tools for three (3) years now, no problems. And I do not believe that even you professional lawncare guys could possibly use the polesaw units as much as I do.
I also own a 290 (brute) and a 192 (ultra-lightweight) handheld Stihl chainsaws. No issues with them either outside of normal maintenance. Hard use weekly, if not daily.