MAC vs PC in the Creative Community

Assumed: we agree that the cost of supporting multiple platforms in significantly greater than supporting single platform.

Method: please set aside your bias and respond specifically to the technical advantages (if they exist).

Question: Given that the applications will run in either environment, is there any technical advantage to running Photoshop, Quark Xpress and the like on a MAC rather than an Intel based PC. Is this a marketing issue or do real advantages exist for these apps in the MAC world?