At the top of this forum are a bunch of links regarding B6.  I have it and I like it a lot.  I, too, began with Bryce 4 and have steadily upgraded each time a new version comes out.  The biggest change in B6 is the ability to use HDR lighting as well as IBL.  

DAZ owns Bryce now so the support is wonderful.

Hugz from Phoenix, USA

Victoria

Remember, sometimes the dragon wins. Correction: MOST times.