Rosie, do yourself a favour, hold off buying Bryce 6 until the end of March, Bryce users have been promised a word on the future of Bryce in the first quarter of this year. It has't happened yet, but Dan Farr (Daz3D) has untill the end of March. It also might be a prelude to any updates of bug fixes.
For me, if Dan Farr isn't forthcoming by the end of march, I am going to go ahead and buy Vue instead of spending my saved cash on a new Bryce.

As for your question, DazStudio is more compatable with Bryce (even though some still get errors) so it's a better choice, but if you do have Poser, there is no problem which ever way you install stuff.