Don't have experience with the 3500, but from what you described your intended usage would be, seems like a good solid ride. Mostly bike paths, light trail (i.e. crushed limestone?) and the occasional singletrack adventure? Seems like it would be a solid rig for that application. Are you intending to commute with it, too?
You may want to ask on this team, there are plenty of Trek riders there, some who might be able to offer you more model specific advice. www.sparkpeople.com/myspark/groups_individ
Hydro disc brakes are great for singletrack, but probably excessive. Avid BB7s are a good solid mechanical disc brake with less upkeep.
Edited by: KA_JUN at: 3/26/2013 (21:01)