Quote - 64bit rendering I think means more that you have more colourspace (2^64 colours vs 2^24 colours). As in hdr and exr images.

No, 64 bit means a lot more than that. Running a 64 bit program (and you need a 64 bit OS) gives you access to a lot more memory and greater speeds. I run 24GB on my home machine, which means vastly decreased render times.