i've been using mine often for 8 months, and the compression is still like new.

i did break the connecting rod, but that was my fault, running it too cold during the winter months.
i bought a new piston/sleeve for about $30 new. i wasn't sure if i needed them at the time, but i didn't. so now i have them ready to go in whenever i do need them. i imagine if you run the engine right, and tune it correcty, any engine should last a decent time.