Just an observation on shifting.
I recently did a 4 day tour with a buddy that I tour with a couple times a year. We also ride together on regular road bikes with the local club. Now on our road bikes I'm always the one behind and chasing, but on our touring bikes, I'm always out front, even though I have a more upright riding position. Well on this last trip I noticed something that I think solves the mystery.
This guy has a very traditional touring bike with bar-end shifters and I've got STI mountain bike style shifters. As we were riding side by side I noticed that I was shifting at a minimum twice as often as him. On the hills, rough road areas, and tight curves he rarely shifted, while I continued to shift constantly into the optimum gear. The reason is because I don't have move my hands and no adjustment is necessary to get the gear just right, just click and done.
Now touring is not a race, but being efficient with a loaded touring bike is a big deal. It's easy to just speed up into a gear that is a little too big on an 18lbs road bike, but it wears you out on a 75lbs touring bike. The overall tour will require less energy and you'll enjoy it more if your less tired at the end of each day.
Anyway, just thought I would share. If someone is choosing or building a new bike, I highly recommend a handlebar / shifter set-up that allows shifting from your preferred hand position. It's safer and more efficient, especially on a loaded touring bike.