Thought I might pitch in with my experience about the iPhone and battery usage on a tour.

I used Track My Tour on my Trans America ride earlier this year, it was great but remembering to save my waypoint each time I stopped was a bit of a pain, but I got used to it by the time I made it to Kansas.

I used my iPhone as my primary GPS, phone, camera (but not my basic cyclocomputer to tell me current speed) and I had my iPhone in a bag on my top tube. The GPS app I used was iSmoothRun and had it going in the background every metre of the trip and I'd upload the ride details to Runkeeper everytime I had WiFi. When I stopped to take a photo, have a drink or find a bit of shade I'd try to remember to add my waypoint, but I often found that I did forget and I'd stop again just to add the waypoint in the app.

I found I could recharge the iPhone battery every night somewhere and in the entire tour I found that my battery dropped below 50% only on a few occasions, once when I did a 10hr 124 mile day from Rawlins, WY to Lander, WY but not too often. My rides averaged about 6-8hrs per day in the saddle. I did have a Morphie Juice Pack Plus on my phone, never needed to use it, but was happy that it was there.

It would be a great addition to the app to add automatic waypoints, stored locally on the phone and then uploaded when back in cell or WiFi coverage. If someone is touring with an iPhone then battery is a consideration, personally I found that additional items like the juice pack don't weigh much compared to adding other devices to do the job.

Having said all that, mine was a tour across the usa with easy access to charge my phone, if it was a more isolated tour, would I have done it differently, yes, would I still use the iPhone with battery backup, probably yes and I'd also add a solar battery charger.