And I have talk to a vendor who is/was worried about having to go through and fix all their old stuff.  And I pointed out that a lot vendors make a product and then sell add on textures to change the look of that product.  So, the question is should be allowed to sell those extra textures?  Or should they give them away for free since they already made the base product?  So it is with the current Dynamic clothing, it was made for the old Cloth Room and works as intended there.  If the user wants to they can redo the cloth in the newer version of Poser OR the vendor could sell an add-on that allows it to be used in the new room.  That is much the same as the user could put in new materials to replace those that came with the product instead of buying new ones from the vendor.  And as far as going forward you might want to charge a bit more for both dynamic options or stick to one or the other.  There is nothing saying that a product has to work in ALL versions of Poser, just that it work in the versions that it says it will work in.

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13, 14