Regarding render speeds and HDRI, Steve did say:

"Though, as with all advanced render options, IBL via HDRI does not come cheap to your CPU, so don't expect a perfect render in just a few minutes. "

So as AS said above, hopefully more will be revealed about render speeds in general during the ArtZone chat Q&A.

I dare you, while there is still time, to have a magnificent obsession. --William Danforth