In my own experience, using cuda when you have access to an NVIDIA card increases the speed even more so. Perhaps you might want to add a comparison to that too. I used to make fractals too and went through the same steps :D
It would be an interesting comparison, yeah. I haven't worked with CUDA much lately though. I was thinking of adding CUDA support so that Chlorine would default to CUDA on Nvidia cards, but it seemed of limited value. The real goal is 1) portability and 2) ease of use, rather than absolute performance.