Short and fast rides, long and easy, it's all good. I'd take the research to mean that I won't need to feel guilty choosing one over the other depending on whim of the moment.
I have to be a little skeptical of the article's conclusions though because I don't see it in the Science Daily write-up they cited
http://www.sciencedaily.com/releases...0405194101.htm It looks like both types of exercise are good.