The Mugens can take a beating. Second only to Xray in durability. I don't see the Mugen guys bringing many parts to the track.
Every car thread on here is filled with bugs/problems/upgrades. Every desighn has its flaws. Some companies upgrade thier kits often to fix the flaws,.......and people complain about that to!
Its really hard to make a buggy kit without some new flaw popping up when production ramps up. Losi has completely redesighned the 8ight in the 2.0 model and they still screwed up the radio tray completely. And thats an easy fix, but they still have that servo problem.
An honest racer is more vocal about the flaws in the kits he likes/owns. So it can be pretty harsh in forums sometimes. Take it with a grain of salt, it is opinion after all. I like to bash my Rc8. But I did fairly well with it.