My current touring ride is a Jamis Aurora. Drop bars, 3x9 set up with bar end shifters. I love the bike and have ridden it a little over 15,000 miles. It has done well on several fully loaded rides. It's limitation is tire width. I'm pretty much limited to 32c tires. I'd like to build something more suited for dirt/gravel roads to explore off the beaten path. I also plan to take it on tour in central America. I moved to a rural, hilly area and the roads are in less than stellar condition. I'm looking for comfort. I've got a good collection of parts that I can use but I'm not opposed to buying new if it makes sense. So here's the plan:

Frame: Surly LHT with a trekking bar. I'm debating over disc or canti
Wheels: I've got a couple pairs of Mavics with different tires mounted for every day use. I'll have a set built with 36 hole deore or XT hubs and Alex Adventurer rims for touring.
Crank Set: Sugino XD600. I believe the spare I have is a 26-36-46. I'll pair this with an 11-34 cassette and possible swap the inner for a 24 tooth ring. If I go 2x10, I'll use a 26-42.
Shifting: Dura Ace 9 speed downtube. I've also got a set of Apex 2x10 flat bar shifters but I'm just not sold on 10 speed for touring. I considered shimano trigger shifters but like the simplicity of the indexed downtube shifters with friction availability. I definitely like the friction front with trim ability. It also keeps clutter off of the bars. I've got a new deore shadow rear and 105 triple front derailleur already, I also have a long cage Rival if I decide to go with the Sram setup.
Brakes: Here is my dilemma. I've got a set of BB7 and a set of Tektro 720 cantilevers with shimano levers. The discs make a lot of sense from a performance standpoint. Rain, dirt, mountains all combine to push me in this direction However, I like the simplicity of the cantilevers, especially for travel in remote areas.

What do you think? Disc or canti? Shifters?