I have Poser 5 and its very clunky and unstable. I don't buy much content from ether Renderosity or DAZ, but I would like a tool to help me rig figures that I model in Hexagon or Carrara. I also like some features that Poser has. I guess my question really is, as a Carrara user, should I buy Poser 7 to help me as a workflow aid. I know that I can rig in Carrara, but it's kind of clunky also.

early reports indicate P7 is far more stable than P5 (OS X). YMMV. I found P5 to be nearly useless, and its rendering functions were about 5 years behind the curve.

P5 on OSX drove me nuts. P7 is pretty solid. However, if the new features of P7 are used, it doesn't play well with Carrara. You can crank out some great renders with P7 but Carrara is sooooo much nicer for that. If you're only interested in rigging up models, I'd actually get P6. For me, it actually loads faster than P7. Additionally, you might be able to get a pretty nice deal on P6 - and it does play well with Carrara. Personally, I like to have a wide selection of tools in the old 3d toolbox to work with. Upgrading to either P6 or P7 will make your life a little easier. Mark

I have never had trouble with Poser 5 and only added Poser 6 because of the special price. If you only use Poser as a source of material for Carrara, as I do, Poser 5 is still a good bargain to have I feel.

P6 can copy bone setup  from one figure to a simular cut figure. Then you just need to adjust the JP's.  It would be better than P5 and as stated,  you can find a cheep price for P6.

I use P7 more now, It is pain to use with Carrara so I still have P6 installed. Then again P7 works quite well with my Vue6I. 

I'm staying with Poser 6 because it works great with Carrara Pro 5.1.  I might get Poser 8 later because it will have more features than Poser 7 and e-frontier seems to charge the same upgrade price no matter what previous version you own.