Stewart Wieck (author of Mage) was a guest at one of our cons, and he's an OK guy. I've been curious about it ever since, but have other priorities for my oh-so-short gaming budget.
But then again, Mage doesn't really mesh into the World of Darkness, and there aren't that many Mage players out there (compared to Vampire players).
And I've never played a Storyteller-line game, not even once. It's like a glaring hole in my gaming history.
