You should not have any problems with content for older versions of Poser working in Poser Pro2012.  In my experience it is the other way around, if you have an older version of Poser you may have problems with content made for Poser Pro 2012/Poser 9.

The DAZ figures all work in Poser, but some products you see that are for DAZ Studio only will not work with Poser.  The reality is that just about all content  from Rendo/DAZ will work in Poser Pro 2012 unless Poser is not mentioned in the product requirements.

The only DAZ figure that does not work natively with Poser is Genesis, so avoid buying content that is made for Genesis, unless you are using the Genesis figure speficilly in Poser.  You will know if you are as there is a Poser Genesis importer (which I cant remember the name of) that you will be using.

Hope that helps

John 

Fugazi (without the aid of a safety net)

https://www.facebook.com/Fugazi3D