I'm up for the modern wheels, too. Especially if you're going to load the thing down. Friction shifting keeps thing simple and adjustable. I wouldn't go with brifters, although I admit two of my tourers have index shifting (one bacon 8-speed, one downtube 7) I've never actually toured on them, though.
If you like the Mountech, and its properly set up and lubed, keep it and bring a Suntour ARx (or any long cage) as a spare. You're an experienced enough mechanic to change that out in 10 minutes on the road.
I disagree that leather saddle is inappropriate for touring "because it's going to get wet." Not with good fenders. Not if you have a grocery bag or two to put over it when you have to park it in the rain.