Stihl and Echo make excellent equipment but after talking the the dealer who sells both brands I'm leaning toward replacing my equipment with an Echo PAS 230 so I only have to maintain one engine. I can put a multitude of attachments on the power head and be money ahead in the process. I already own an Echo SRM 2100 so I won't need another trimmer for a while but a pole saw, pruner, edger, etc. sure would come in handy.
The down side is when the engine does need work, you loose use of all your equipment. The most common failure lately in my neck of the woods is the carburetor due to Ethanol related problems.