The only real "fault" I found with JH13 was a lack or void of midbass. You have this massive deep extending sub bass but then there is a void all the way up to the midrange. Yes, it is intentional to add to the transparency but I found it a little off sounding. The JH16 fills in the absent midbass yet still has tons of clarity and transparency. It's just not off the charts like with JH13. Great IEM though. More unique sounding than JH16. Sort of like JH5, JH16 and even my W3 are the same family type of sound sig but JH13 is a whole different beast.
What I found with the JH16FP was it had too much midbass. Like off the charts mid bass that bothered me a lot after many many hours. It was relentless on female vocals. I'm going to get the JH13FP in soon so hopefully that'll ease up my ears a bit.
I guess some people like the mid bass and some don't.