Hi Michael,
I too was a (heavy) user of NX2 but since it was clear that that was a dead end and NXD would never live up to it, I have fully switched to DNG and adobe camera raw. Like you, I found that the NX2 embedded jpgs are of good enough quality for almost anything, even printing. So I have not bothered to convert them to tiff, and will not either.
I still have nx2 around (as long as it works, it works), but if I ever need to edit an existing photo, I will edit it with ACR, anew. The results are different, but at least as good and mostly even better I'd say (but that is likely also to my advancement in editing skills). Sure it is some extra work, but I only need to do this occasionally, so it isn't really an issue.
Hope this helps,
Hayo