Personally, I'm hoping that both can come to use a standadised plugin format and that one or both will release an SDK. Poser currently ships with a Python API, which offers most functions of the Poser SDK (which can be licensed from Curious Labs). The Python scripting host offers enough functionality not only for custom im/exporters but also for more complex plugins as MKParticles or Ockham's deforming collision detection have proven. Also, I have a plugin in the works that uses 3Delight for background rendering in Poser 5. The product page of DAZ|Studio talks about Python plans too, but it doesn't say if the application's API will be compatible to Poser.