This "study" was done by... an investment banking firm... and one that had just put out a buy recommendation on at&t... Yeah... real impartial study... bwahahahahaha. What a joke.
They blur the line (much as at&t does in their commercials) about how fast their network is (and yes it is fast, when you are at or near one of their high speed towers, and no congestion happens to be going on) versus how well the coverage is overall. Note how, while VZW speeds may be lower in the areas it "lost" the speeds were still decent. Now compare that to what happens to at&t's signal in Times Square and other places where it lost.
It is undeniable that HSDPA and HSDPA+ is faster in theory than EV-DO. But the fact remains that you are not getting those ideal speeds everywhere, even in locations such as Manhattan which is supposed to be a solid blue area on that 3G map.
But in the end... are you really going to believe (or care) about results put out by a investment banking firm? Piper-Jaffray has some at&t stock to unload and they want to push the stock back up so they can bail before that iPhone exclusivity period ends.