buying a bike and replacing parts you don't like comes out more expensive than just buying the bike you want, so i wouldn't go that route. the 2010 gary fisher seems like the way to go on this, put the big money into it up front, and take it from there. disc brakes are where it's at, so i would get something with disc brakes, i would stay away from v brakes if you could. as for 29er vs 26er....as a tall guy you might like the 29er more...you gotta ride them and see what feels best.
it comes down to this: all bikes are different. test ride as many as you can and get the one that is most comfortable that you can afford. if it's out of your price range....start saving. good luck, let us know what you end up with.