I love my Mac. I use MegaSeg for my show software.
For what it's worth, mine is NOT a dedicated machine. I restart it before events, but at home, I use it for everything.
The only times I've had problems at a show were:
A) I bumped into the FireWire plug, knocking it out of the socket. The software, and OS, didn't like that. Fortunately, that happened during toasts. I restarted before the toasts were done.
B) My external hard drive was failing. Switched to CD while swapping the drive.
At DJ meetings, I'm constantly hearing DJs that use PC talk about the problems they have. The one other member that uses a Mac, looks at me, and we smile.