They do speed up your work flow because the UI is better thought out though - that is a fact. Better efficiency and speed with a more intuitive UI = time for more creativity.
I’ve been a PC guy for over 13 years. Bought a Mac this spring and just took a job where all ID’ers work on Macs. I have no desire to work on another PC ever again.
Also, you do not have to even restart anymore to run XP/Vista on an Intel Mac - Parallels runs all 3D apps quite nicely (that includes Rhino, UG, Solidworks, 3DS Max…).