The only possible way it can strike you as bogus is if you have never taken both of them outside and tried to read them. If the focus group was conducted in an office, then the results are basically meaningless.

I use my kindle on my boat. 99.9% of the time I'm sitting in the sun reading it. I can do that with a book, and I can do that with a kindle. The iPad or anyother backlit screen is just not an option. I can barely see my cell phone or camera screen on the water, but I read the kindle becuase it is a fundamentally different technology.