I have Stihl Kombi system, no difference in handling to a dedicated unit of same engine size and power. The coupling pieces do not add much weight to the overall assembly.
My preference is to go with a lighter / smaller engine dedicated straight shaft string trimmer. I don't need a lot of power for the string trimmer and that is mostly used so being more nimble and lighter is desired. Simple and light is paramount. Get in, get out fast. For edgers and rotary sweepers, I'd go with and a larger or largest engine split boom power head because of the power requirement.
I really don't like the newer 2 stroke/4 stroke hybrids, too finicky to start cold. The Stihl KM90R power head does have lots of power and torque once it's warmed up, although the throttle modulation is touchy.
This message was modified Nov 11, 2010 by aa335