A quick correction: OP describes Arlo Belshee's paper as a "research paper," but it's more properly an experience report. Arlo was working in a professional environment with a team of programmers. That team tried a variety of techniques for improving their productivity, from "no pairing," to "extremely rapid pair switching," and measured the results. I have no doubt that they saw the results they claimed, and that promiscuous pairing worked well for them in actual practice in a real, professional programming environment.

And... this is an experience report. Their "experiments" weren't controlled, blinded, or anything like that. So there are almost certainly contextual nuances that haven't been discovered yet. What worked for Arlo's team won't necessarily work for your team.

And... this is true of nearly all software development techniques. There are hardly any controlled, blinded studies of software development techniques that are worth a damn. So if Arlo's technique seems intriguing, try it. Just don't (a)hold it up as proven technique, because it's not, or (b)get angry that it's not scientifically proven, because chances are very, very good that none of the software development practices you love have been scientifically proven either.

PS: An interesting followup experience report from a team at Microsoft that tried promiscuous pairing for a while: http://dl.acm.org/citation.cfm?id=1155480.