I've had the exact same saw (but the Hitachi version -I'm in Japan) for several years. I indeed use it for a climbing saw and for when hiking up the mountain. Its light, cuts fine for what I got around me (mostly cedar and cyprus) and balances well in the hand which is good in the tree. Usually cold starts in 3 or 4 pulls. Very easy to chuck in my pack when going out deep. I also buck any stuff I got that's less than 15" (usually softwood). And I have to say that I have not been kind to this saw and it has taken a severe beating, but it is still running like a champ! The engine just keeps going no matter how much damage the saw has gotten.
And the list of evil I put the saw threw is almost impressive. Dings, drops, left in the rain. For a while the chain oil line was clogged, which made it pretty hot and caused me to overheat it more than once, which eventually melted the plastic around the clutch so much that it has rendered the auto-brake useless, but I just ripped out the lock-spring and kept on cutting. In one of the over-heatings during a rip cut the internal dynamo screws came loose, which caused it to get slammed by the fan, making all the metal layer in it completely bent to heck, but I just pintched them as flat as I could with some vice-grips, screwed it back in, and it started right up! I thought it was a goner with all the oil pump trouble, but I finally took it all apart, cleaned it the best I could, and now it spits oil great. I also broke the throttle linkage line in the handle but could rig up a new one with a bit of wire.
Sometimes though, I've noticed it gets kinda hot when I work it hard (it also has two broken fan fins), and this is with a working oil pump. So it if this happens it continues with spontaneous combustion (detonation) even with it switched off for 20 seconds or so. But I've never had any piston or bearing problems. I liked it so much I went out and got a Hitachi brush cutter (like a weed wacker) and that thing runs just as excellent. I must say, for the price, Hitachi (Tanaka and Echo are sub-brands) makes some durable stuff. Enjoy!