Thanks for undertaking it, Tim. If yo do it again, please try to do a triangle evaluation.
I was looking for that too, based upon what I already knew about the test and Drew Beecham's very succinct explanation of when, why, & how the triangle test is used that you can find on the Basic Brewing Radio Podcast (while plugging his and Denny's book).
They did have more than two beers to test, so I imagine that could have used a system of multiple triangle tests, followed by more detailed sensory analysis to describe any differences in the beers. That said, what they did to answer the question "Does decoction make better beer?" seemed okay, just perhaps didn't get at the minor differences in each beer that may be detected and described by using something other than a score sheet. Different beers can score very similarly but taste/smell/feel very different. It was cool to see this work in print- nice work!