I think that the demo versions of the JH13s were not a very good fit and no seal, making the sound bad.
I had another listen today at the JH 16 pro. These were demo versions with small foam thingies attached, the fit was not very good so I had to put pressure on both pieces to get good sound. Compared to my Ie800s.
Bass: extension ok, not as deep as ie800. However bass in JH16 was better defined and more articulate, ie800 was a little muddy in comparison.
Mids: a bit more forward kids than ie800. Great resolution. However ie800 is also great. Tie.
Treble: In comparison, ie800s treble is slightly harsh and sibilant compared to JH16. The treble is more pronounced in ie800, sound is a bit airier/brighter at the extreme treble.
Summary: JH16pro is a bit more mid-focused than ie800, with good bass, although not as deep, and slightly less treble emphasis. Maybe more neutral. However ie800s kids are very, very good.
I played straight out of IP5s. Ie800 were more hard to drive and required higher output than JH16.
I like the JH16pro. Considering them or the JH Roxanne. Had my ear impressions made today!
In my experience, the JH customs sound significantly better than the demo versions--enough that it is very difficult to draw meaningful conclusions about the earpiece without hearing the finished product itself.