Okay, looking for my first Mountain Bike. I've ridden others, but am ready to buy my own now.

I have a couple of candidates:

New Specialized Rockhopper Comp Disc
New Gary Fisher Marlin Disk
Used 2006 Kona Hoss

Of particular note is that I am not a small fellow. I'm 6' 275 lb. The Used Kona seems like a good deal, but is a 20" which is too big by a hair. My biggest concern is in the fork. The Marlin has a Dart 2, the Specialized has a Dart 3. I've been told varying things on these, some say they can each have "stiffer" springs put in, some say no. Some say they'll be fine for my size as is.

Provided the Specialized and the Gary Fisher each feel right, which way to go?