Here are links to two bed-edger threads that you might find useful:
Best Bed Edger Vote and
Mechanical Bed Edger.
I just took delivery of the Bluebird Bed-Bug last week, and got my first few hours in running it on Thursday. It impressed me as a very well-designed, easy to operate machine, and 5.5 hp Honda is just a great engine. The big drawback is in heavy wet clay soils, where the Bed-Bug has the cahones to cut the trench, but the soil clumps up in the hopper, impeding blade travel and bogging the machine down. I don't know if the other machines handle such soils better, and I look forward to a little drying out so I can get a better handle on how the Bed-Bug performs in optimal conditions. Finally, maneuverability is excellent, although defining a bed edge walking backward is tricky.
Good Luck! (and like Bill says, check out the GTX search engine to mine for answers to other questions you might have)