I've been a casual reader (and even more casual poster) of Rendo and Daz forums for years, and I never really got a hint of any bad vibes between the two sites.  I know both sites are really strict on the porn aspect of Poser and Daz Studio, and do not allow links to such sites. But they do present a professional respect and admiration toward each other.  At least that's how I perceive it.

And the occasional Poser vs. Daz Studio debate will pop up, but from what I remember, they were all usually very civil and the last comments usually made were "use whatever feels right to you, they are just tools for your creativity".  Which I totally agree with.

I think both sites have equally good and bad aspects about them.  If anything I sense the "community feel" slipping away from both sites to make way to a large "K-Mart" impersonal feel.
They'll always be the forums, and friends in the forums, but you get a growing sense that you are not part of a "people-first" community any longer.  Definitely not like in the old PFO days with Willow and Grey (for those of you old timers that remember)