No, you don't have to dig. But I can only give you a comparison with the pre-FP JH16. I have no idea what the FP version sounds like, but I'm willing to bet that besides increased detail due to proper phase alignment, the spectrum presentation is pretty much the same.
The Roxanne, is very different in one respect. The high frequency response (say anything in the upper half of the spectrum) is much better. Like miles better. The amount of detail (or even noise in bad recordings for that matter) that the Roxanne's present is mind boggling. Even at fairly high bit rates, if there are lossy compression artefacts they are evident. Because of the Roxanne's high freq response improvement, when transitioning from the JH16 it may seem as if the Roxanne's are mid-recessed (even more so if you increase the bass). They are really not, it just takes some adjustment time. I've had them for 3 days and that's all it takes. The problem is that the JH16 was really not great with the upper half of the spectrum, so most of what you hear is the lower half of the spectrum (say... 10K and under). Anything above that is not prominent like it is with the Roxanne. When I put on the JH16 now, they sound muffled, as if the upper half of the spectrum is obliterated by the lower half.
Besides that, the bass is as good as you're used to. The difference is that now you have control. If you like the amount of bass that the JH16 puts out, you can have that. But if you don't (like me) then you can now dial it back. I absolutely adore them at the 8am neutral setting. Much better than the boomy presentation of the JH16. I've always used EQ on my JH16 to reduce anything below 200hz by about -6db, so that the midrange and the high frequencies could stand out more. Now the pot is doing that job, Roxanne sounds amazing plugged into almost anything without the need for equalization to tame the bass.
In conclusion, my JH16 are going up for sale in the forums soon, I think that sums it up.
Hope this helps.