As a Poser2010 user, i can understand what vintorix and the OP mean. With Poser 2010 they built in gamma correction into Poser (someone might have read about it). But they built it into the pro versions only, not the cheap versions, probably not the best idea they had, but anyway: i think vendors want to get the most customers, so they continue to make complicated materials that somehow fake gamma correction with the cheap poser versions, some of them likely unknowingly. Because DS has gamma correction built in, too, the vendors would get similar problems trying to support DS as they would by trying to support gamma correction in Poser2010.
So when a vendor writes in the README "Materials for Poser only", my brain automatically translates this into "Poser 5 materials only, because i do not know what gamma correction is, Poser2010 users beware!" (Of course they cannot write it literaly, because if they do not know what GC is, they will only see that it does not work, not why it does not work). So when buying models from vendors i do not know, i look if there are DS materials included, even if i never plan on using them. A vendor who is capable of creating materials for both DS and Poser should have have at least a rough understanding of what gamma correction is and how to deal with it (at least i hope so).
Unfortunately the reverse is not true, so as a fallback option i look if there are Poser4 or PoserProPack materials included. Those usually seem to be very simple (so called click-and-render-crowd materials) and probably can easily be made to work in both DS and Poser, regardless of the version. Most of e.g. Stonesmason's materials are of that kind (who btw does not seem to have major problems making good stuff for both DS and Poser).
So the net effect is, that if i want to know how easy it would be to use a product in Poser2010, i have to look if that product supports DS or Poser4; and this sounds a bit awkward, does it not?