Well, I am not experienced enough to be categorical here, but based on the data I looked at, sites like MMR average gradients to such an extent as to hide the most critical sections. (ex. one km at 8% with 200m at 25% will show as a section with a (benign) 10% gradient. On some sections, the terrain may be such that there are many many problematic sections. Although it may look like elevation gain is a critical metric, steep gradients are much more problematic.

We'd be two adults that there wouldn't be such fuss. But with kids...

hmmm.... are you aware of the tribulations of Vesta team? (a Volvo 65' that has participated in the previous Volvo ocean race). They hit a reef in "the middle of the ocean", east of Madagascar. Most likely their route had been planned at a small scale, so small that the tiny reef didn't show on their screen. Incredible pictures. But the really mind boggling thing is the root cause of the accident. (see the official report here). Quite incredible that no-one ran a large scale analysis. Quite incredible that large-scale analysis is not a mandatory feature of routing softwares.

So yes, it is great to have "the big picture" but if it is not fine grained enough, it can actually lead you to a false sense of security. (writing this, I realize that bike touring is unlikely to lead to dramatic situations -- please keep in mind that I am trying to figure what is a reasonable route for our tribe.)

FWIW -- I ran the data for the entire EV6-EV13-Istanbul route. Took a couple of hours (minutes for the actual charting -- more time was spent on locating GPS traces.) I would like to add that my understanding of the Sierra Cascades profile may have been caused by crummy routing. Will try to find the definitive tracks before we make a final decision on this.

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on a related note -- anyone knows how to calculate the maximum achievable gradient? I mean, a cyclist can deliver a finite amount of watts. So this figure has to be determined by gears and weight (air resistance not being crucial when you travel at 6kph (again, that will be useful to achieve a fair balance between our (low watt) pre-teen and (average watts and loaded) adults.