As others have pointed out, Studio and Poser are heavily compatible. The main area of incompatibility is the "Material Room", aka shaders. Studio, up to version 2.3 could not use the same level of sophistication for shaders but that has changed drasatically with Studio 3.
Some types of magnets are also incompatible but in my experience those are pretty rare.
I own both Studio and Poser ande I stopped at Poser 7 and will nto upgrade to other versions unless they bring some major improvements including a complete re-write of UI. I find Poser inetrface atrocious, clumsy and very in-the-way of the artist. Studio's UI is much more streamlined and usable, IMHO.
When in doubt contact the vendor of a product and ask about Studio compatibility, which is also a good way of letting vendors know of your interest in Studio products.

Paolo

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