Back to the audio dropout issue... I contacted my dealer about this and he said to return the W80 to the distributor, who confirmed the problem, and after consulting Westone sent me a brand new W80. Which is great.
However, while I was without my W80, I went back to using my W60 and started having the exact same problem. Actually, I had some audio dropouts with the W60 before but figured it was to do with the cables rather than the earpieces themselves. Sadly, my W60 is now out of warranty and pretty much useless for anything other than reshelling.
I'm grateful to have a brand new W80, but it seems to me almost certain that the same issue will occur in a year or two, by which time it will be out of warranty, and I'll be out of luck. Westone used to have a pretty good policy on out-of-warrany replacement - originally there was a very generous 75% discount, which was then reduced to 50% and is now only 25%, making it uneconomical for international customers due to tax and shipping costs.
So my viewpoint is that Westone is basically selling disposable $1000 or $1500 earphones, which can hardly be considered an "investment". Right now I feel that the move to MMCX has been a mistake, and other manufacturers were right to stick with the 2-pin connector.