"They ignore P5 completely. Maybe they have information, that there will be no further Poser development and they see the future in D|S."

Let's be honest... the only real reason to not support P5 for Daz is a political/marketing one and not technical.

For example it would be a trivial matter to create P5 shader set-ups to apply the Daz maps and textures to apply correctly for Firefly and look as good as they can. The changes are well known and take very little time but it woudl be a nice thing for them to have been included. Similarly it would be fairly trivial for some of the props and other items to come with Poser5 settings applied for materials.

That's something simple that could be done... even if they did not want to support dynamic cloth or dynamic hair.

I don't know what Daz's plans are for D|S and now Bryce - but it sure looks to me like they are moving away from the Poser application - and I don't know if they will make it worth forking in that direction.