I've been running the JPX .21 in truggy for two seasons now. I'm on my second one (first was AB modded, this one is stock). Even with a 9886 and a short conical header, they make more than enough bottom end to throw my Losi's around. It's almost too much at times. The top end is also fantastic, especially when modded. In my experience, this engine rarely breaks 220f, and gets decent runtimes (although I haven't been able to hit that magic 10 minute mark, more like 9 min max). I really couldn't be happier for the price.
Longevity is excellent. Maintain it like any other engine, and it will last a long time. Watch the rod, as the pinch from the factory is pretty brutal. I'd recommend replacing the rod after the first couple gallons. Also, like itsshemp mentioned, they can be somewhat cold blooded, so make sure you get them up to temp before you touch the needles.
-Howard