Depends on how long you're trimming. If it's 1/2 hour at a time then you probably have some rough areas that need more power and handlebars to control it and a harness to spread the weight. If it's short duty then it's overkill, bulky and not worth the bother to get them, assuming as others mentioned that you can't have a metal blade on it... UNLESS you have a bad back. A long shaft, harness and handlebars is much easier on a bad back.
Then again if the vegetation is light and the duty is short "enough", the time may have arrived where cordless electric makes sense. Pushing a trigger to start a cordless is easier on a bad back than pull starting. I wouldn't even consider gas if you can get the job done in ~15 minutes or divide it up so you don't need multiple or high capacity batteries, which start to get expensive for the decent 40V or higher cordless.