When I did this commercially, we used RedMax blowers and trimmers... that was many years back. They ran flawlessly and were not treated kindly at all.
That said, I have an Echo line trimmer and blower now and they never bobble...one to two pulls to start even after sitting for months. Both are 15ish years old and haven't had a thing done to em...ever.
This doesn't answer your question on power or cfm, etc but from a reliability perspective, I can recommend Echo and RedMax
Thanks
