Some interesting points there bingobus, thanks. A google search highlighted some decent road rides out along the coast but like you say, a fair bit of the city to go through before you get to those roads. I think a poplular ride is up Froome or Seymour, then straight back down. I'm going to bring my road bike anyway, if nothing else it's a way to get around the city.
What you described is what I expected for MTB, massive climb followed by massive descent, rinse and repeat as many times as you can handle. There's a place I ride in Scotland that quite the same but on a hill not a mountain, same fireroad climb, mutiple descents from the top. I'm not that really into XC or DH as such, just like riding trails that are technical 'for me'.......which obviously varies between people. I ride a local DH track on my Slash which I'm sure is going to get blown out of the water on an easier shore trail!
Craw, I quite like stats, but mainly for the elevation gained, doesn't sound like I'm going to be dissapointed there :)