I wonder when people will realize that light weight doesn't always equal ease of use?!
If you want to reduce the stress on your arms, get a quality unit with bicycle grips and a back support (not strap). A bit unweildly to put on at first, but like "guiding air" when you're using it (for trimming along straight objects, coordinating your leg movement is a little different if you're used to D-handle...but not hard to learn). If you buy quality, their's a good chance the vibrations will be much less as well - also reducing stress.
My wife was positive she liked the little Craftsman better (their "medium quality" unit), until I finally talked her into trying the Stihl instead of just picking it up and saying "it's too heavy." I won't complain about the Craftsman for the purposes I bought it (on sale with the pole pruner attachment for the price of the trimmer alone), but nothing like the Stihl.
