Yes I have heard and have the honor to have JH himself to put the JH13FP into my ears!
Oh well, i personally felt that the old JH13 is still better than the FP model, but that's just me i guess.
What i like about the JH13FP = much more clean, clearer, very fast, clinical, highs are well extended and lows are pretty decent. Staging and imaging is good along with superb instrument separation. in fact, i feel like JH13FP is the CIEM for studio monitoring purposes. It basically throws everything to you like how it should suppose to sound without any coloration imo.
What i don't like about JH13FP = far too aggressive and "furious" to my liking. extremely flat and linear-like. short listening period is tolerable, but after, say 1 hour, i would probably get a headache.
What i like about V6 = clean, clear, and decently fast, highs are smooth and slightly coloration to the mids with a hint of sweetness. lows are decent and neutral-like. staging is slightly smaller than 13FP but imaging could be either near or on par with 13FP. (i feel that V6 is the cheaper version of the Unique Melody Miracles, with very little compromise here and there).
What i dislike about V6 = sub lows (23hz or less) are abit unstable in its decay and resonance. Mids are a bit thin to my liking, but i'm still pretty OK with it. Instrument separation isn't as good.
I hope this helps.