To me, Poser 7 was worth the upgrade.  The multiple undos alone is worth the price of admission, not to mention faster rendering, more detailed previews, and better memory handling.

I don't currently use the cloth room, so I wouldn't know about that.

Universal Poses aren't very universal, I've gotten poor results applying them to Daz figures, although they might be okay with the e-frontier people (who I rarely use).

The morph brush is cool, but I've not gotten much mileage out of that.

I don't use the organization feature because it won't work in Daz Studio or Carrara, I simply use P3DO Pro Explorer to organize my runtime libraries.  If you only work in Poser the categories probably would be a time saver once they were set up.

Poser 8?  We've not even got Poser 7 Pro Pack released yet (which I probably won't get--unless they did a major UI overhaul).