Granted Ryobi are marketed to joe homeowner, but I have a '96
310 bvr (new); '97 280 r (rescued from dirt floor of a shed) and a '97 766r trimmer (new), these all work perfectly since new, needing only fuel line and filter changes. The bad experiences many people have is due to improper carburetor setting, owner error with fuel / oil mix, neglect and lack of owner following maintenance directions.
The 31cc engines are really tough units, the rc airplane people love these engines for airplane duty.
Parts are easily available for these units from MTD and are inexpensive.
My only odd experience is the reed valve limit stop eventually rubs on the edge of the connecting rod big end, so that needs to be checked for clearence, a double gasket on the intake manifold solves that problem forever.