Briefly.
The JH13 non freqd vs. the JH13 freqd: made my "old" JH13 sound slightly veiled (and that's saying something). The "new" JH13 sounds more linear, with even more clarity, with the slight subtraction of bass crunch down low. The analogy I've been using is that someone took a VERY clean window and applied yet another round of squeegeeing to it.
The JH16 I had only heard in universal demo mode before, but these sounded more colored to me (in a good way). Bass seems tipped up a bit down where you can hear the real crunch of electric guitar and bass in a rock track.
The JH16 has an even more fun sound to me now than before and the JH13 has a more serious, straightforward presentation. I should point out that I don't think the JH16's coloration makes it inappropriate as a reference, which is part of why I like it so much. It is a fun headphone, but Jerry didn't do anything to make it sound ridiculous.
I hope that helps.