I work on Macs too a couple of hours per week, but I hate every minute of it...
At the beginning I was wondering why a book made on the Mac version of QuarkXPress has so many files (sometimes only 2 pages in a file), but soon discovered that if a file has a lot of pictures in it, after viewing a couple of pages of it the "Not enough memory to accurately display picture" message appears instead of the previews. And only a system restart solves this problem (for a while). The PC version of QuarkXPress had that problem with Win3.11, but never on Win95 or later.
And the Mac-keyboard is a real pain in the fingers: for example, the home/end keys will take you at the beginning/end of the document (which is a very very rarely used thing to do while working on a document), and if you want to jump at the beginning/end of line (which I use more often), there's a quite odd key-combination for that: Option + Alt + cursor left/right.
I think those who say "Mac is better for DTP" never worked on PCs, so they have no clue how an ergonomic computer looks like...