What a good article this is.
From the wheel builder point of view the 26" wheel is a much stronger wheel and when it comes to heavy loaded / long touring then the difference between the 2 sizes should not be ignored.
Now, this gentleman has access to information that only those people touring around the world might experience.. wheels with thousands and thousands of miles. The average tourer will probably never experience this. Maybe this is the reason why the choice for building wheels to support very heavy loads are very limited nowadays. It's hard to find 700c rims that will take 40+ spokes, even when looking in tandem specialist stores.
Now, should the average tourer be worried about their 700c wheel being less reliable? I don't think so, most tourers I know don't exceed the load for their 700c wheels and they don't do the kind of mileage this gentleman was talking about. Although he did say that 700c wheels failed just after a few weeks but those wheels were factory built wheels with poor quality spokes.
Most tourers would go on relatively short tours, 1, 2 or even 3 weeks so as long as they have well built wheels I think they have little to worry about.
Tourers doing long tours, are experienced tourers and they have a pretty good idea of what is required, they carry the kitchen sink so..... they could not hope to do a tour like that on 700c wheels without risking serius problems.
Our Emma
@SatNavSaysStraightOn and her husband did a long tour across continents, they are experienced tourers and they had the right equipment for that, expedition bikes with 26" wheels. I've seen one wheel and it looked like it just came off a tank
So, horses for courses.