I think there are a lot of ways to think about this. But first of all, I should tell you that my context is that I was a Canon shooter until I jumped over to the D7000. I had Canon full frame (5D) and APS-C (DX) cameras, and used to shoot weddings (so I am into high ISO capability).
I think there is a certain amount of prestige that goes with full frame, but if you have been a D90 shooter, I think the D7000 will suit you fine, and the DX lenses will save you from lugging around some weight. Practically speaking, your only loss will be emotional.
I'm not saying there aren't reasons to go FX, but I will say that when I put full frame emotion aside, I couldn't be happier with my D7000 and haven't yet found a reason to really want or need full frame.
As for pixels, I also don't want any more. I'm pretty maniacal about my backups and I often shoot in quantities. It is also not unusual for me to shoot RAW + JPG. I'm sitting with 7TB of disk space on my desk and I don't need that to grow any faster because I've now gone to more megapixels. I also don't need my editing of file transfers to be slower because of larger file sizes. These file sizes are big enough to do anything that I can ever think of.