Again, you shouldn’t be trying to compare render times with other engines in this manner. I could demolish your mental ray time, for example, in the same scene and with higher quality - with only my Phenom 1100T. What this shows is that you don’t know the other rendering engines well enough to optimize them, and thus all your other times are irrelevant if not outright deceptions.
I think you’ve got a good product, even though (just like the rest of these renderers) your math is inherently flawed. I think if you were to apply modern physics you could further reduce your rendertimes, and then you would have a way to really compete.
To test my theory, please define a photon for us and how your scene interprets them.