Quote - oh for crying out loud...

sphere with 100% reflection, same hdri, one pixel render for antialiasing in carrara and default aa settings for bryce. bryce takes 8m14s. carrara does it in under 30 seconds. end of story.

WOW! look at the range in that Bryce pic! Now that's HDR.
You can get something close to that with Carrara. I've found that by checking 'Full Raytracing', 'Full indirect Lighting', 'Light passes through transparencies', and enabling some low percentage caustics, you can get sort of close to Bryce with Carrara.  You'll have to fake specular transmissions, since Carrara won't calculate those. Carrara's non distributive raytracer is, of course, never going to be able to equal Bryce, but it can get close. Don't expect 30 second render times though.

Friends don't let friends use booleans.