The mathematician may have better logical skills, but the artist has more free time to practice ;-)
Maybe the other way around?
The artists often are extremely intellectual, and might also be superpedantic craftsmen, and they might be in timetrouble.
Well this topic is well under way. I should go to sleep so I'm not going to read it, but I wanted to say that I think chess calculation is really more of a spacial awareness, that doesn't have a whole lot in common with mathematical calculations. Also, I can't think of any occupations that would indicate a heightened or diminished capacity for chess aptitude.