I use shadows because I find it impossible to create a realistic render without them; that having been said I experiment a lot with lighting in a scene before I do a final render.  The only time I wouldn't use shadows is in a simulated studio portrait set up.

I have been a long time Poser user back to Version 4 by Curious Labs.  The Pro Pack 4 had real improvements that I could use (multipane viewing, etc.).  Most of what is in Poser Pro 7 is not stuff I will use--although it would be good to have the performance enhancements that people say they have with it.  Consequently it's not worth the money for me.  If I had the money to clunk down $200 right now, I'd buy the $200 of Quidam and experiment.

Having had bad experiences with Daz Studio after version one; I would be hard pressed to to spend a lot on an enhanced version.  I would only do it if Poser were shelved and it was the only figure rendering program available.  That having been said I'd perfer to upgrade my Carrara to the most recent version.  It's come along way with natural environments that won't crash my computer the way Vue has.

I'm hoping for the best for Poser 8.  I was not dissapionted with Poser 7 except for the fact that "Universal Poses" don't really yeid the results I'd hoped for.  The multiple undos was worth the price of admission alone to me.