I don't know what the actual reliablity of UE's products is. They clearly have their fair share of failures, but whether it's an unusual number relative to the competition I have no idea. I'm personally a bit skeptical, but that's just my gut. The housing cracked apart on my super.fi 5s after about three months worth of daily use and you can find a lot of reports of this same problem, including the claim that they had changed the way they were built to prevent it... so, uh, why did mine break in the same way? Me, I'm still waiting for the person who had super.fis or triple.fis for at least 18 months, used them regularly, and hasn't needed to send them back for an exchange. I'm skeptical enough at this point of UE's product reliability that I wouldn't bet this person is any more real than bigfoot or the loch ness monster. However, since these triple.fis do sound oh so very good, I would be happy to be proven wrong about that unfounded suspicion
On the up shot, what usually kills their products is that their plastic housing is prone to breaking apart, and, sometimes an armature dies. The metro.fi series is not subject to either of those problems. On the other hand, their dynamic driver series are too new to know anything about with certainty.
The only thing that does appear certain is they do honor their 2 year warranty without quibble: you have receipt, you send it back, they send new ones for anything that looks remotely plausible. My complaint, and why there are so many posts in that thread is that they handle this part very, very unprofessionally.
What I have learned from this three to four week frustration is that you need to call them, and you need to demand they send a replacement immediately and you aren't taking no for an answer, otherwise, they seem to do things at their own pace without keeping you updated.