I heard the JH16Pro demo pair at RMAF this weekend, and enjoyed them. The bass was NOT overblown as I feared it would be and was actually simply fuller sounding than my JH13pro, and the JH16 demo had better focus and instrument placement in the bass than that of my JH13Pro.
The 3 sound tubes also seemed to improve the mids, and in my opinion the mids were more present and even level with the bass. I know the demo units can sound a little different than the custom fit version, but I would want that they would sound exactly the same if I ever got a pair.
That is my impression as well, so I'm using them interchangeably source/interconnect-matched. For example the WhipMOD/Fat Boy Reference WhipLOD combo is simply too much with the JH16s because of how that giant LOD handles low frequency punches, so with that I always switch to the 13s.
For those of you haven't yet seen it, here is a very nice, succinct interview with Jerry Harvey about the JHA top-end product lineup and differences between them.