Tomscy2000 and ljokerl didn't like them very much either, a_recording preferred the FXD80 to his XBA-4. I'd like them if they were my first IEM's (which to most consumers, they are), and I can see that some people like them since they 'sound like dynamic drivers', but you may as well just use a dynamic driver then. I even preferred my Vsonic GR04 (which, I have a feeling is a Sony driver or Sony driver clone / improvement somehow ftr).
Apart from the drivers themselves not sounding like your typical higher-end BA IEM (which I was hoping for), I think the main issue at least for me was sensitivity to their crossover-less-ness, something like this -
http://www.diyaudio.com/forums/multi-way/221643-active-vrs-passive-35.html#post3210434
I have a feeling the new JH13 and JH16 "freqphase" is using a DSP technique like that. Digital crossover correction and / or a time-error correction of some sort. I did distinctly prefer the JH11 demo unit to the JH16 on three seperate trials, so I believe the marketing when they say they've improved on the JH16. Then again, we shouldn't really use digital DSP with anything in acoustics. Then again, if the JH16 was flawed all this time compared to lesser-driver CIEM's, they've already pushed quite a lot of marketing on us.
I'm sure you've already seen this, but I'm posting the link anyway so other users in the thread can see it and try it, if they have an iPhone -
http://accudio.goldenears.net/
It should finally shed some needed light on flat frequency repsonse, and / or equalizers.
As for the JVC IEM's, try them over-ear with a deeper insertion, it really improves the spatial presentation IME.
The only good ones are the XBA1 and 3, but the latter is more noteworthy. Joker liked XBA1 not the XBA4, which isn't surprising. Can't speak for Tom. Can't speak for the customs, have yet to see something from a custom that catches my interest, freqphase is a cool idea to fix inverted polarity, but the differences seem overblown. Accudio app is garbage, I won't even bother, someone will write an article as to why soon, so look out for that. No big difference with deep insertion, bass still too bloated and treble is too sharp, not to mention recessed midrange. The FXD70 has lots of potential though, but it's higher treble is so sharp like the 80s, it sets back the midrange and tonality, shame cause it's really nice otherwise.