I have to admit, I use both and Vue certainly has its good points. Here's my impressions if anyone is interested:

Vue has much better vegetation than Bryce. And now Vue 5 has rendering options that are worth the $200 price tag (for Vue 5 Esprit), ergo: Global Illumination, Global Radiosity, true HDRI support. I do have to admit that Bryce's materials (presets or made from scratch) are much better than Vue's, and Bryce's terrain editor is second to none as far as I'm concerned. I still haven't figured out how to make a decent looking mountain in Vue, whereas Bryce I can pop out a beautiful one in about a minute and a half.

I do still eagerly await Bryce 6 (5.5 I think is going to be nothing more than a small upgrade). I'll just wait and see what Daz does with it. I'll probably still pick it up because I do love Bryce. But Vue, I have to admit, is setting the standard right now. Daz has their work cut out for them.