My academic background is in music, University level. Yes, music can be a real performance enhancer, especially at training, and more importantly during anything which could otherwise be fairly boring. Now the article you mention raises one important component I've been studying over (for years now). It is the association of music tempo, and cadence (swim, bike, run, skiing, etc)...
Personally, my training regiment would normally be considered as very very boring. I solely train on the Lifefitness Stair Master 9500r (sometimes called slightly differently depending on the year of release). It's a stepper. Normal training cadence ranges between about 105 and 130 rpm, but mostly around 112-120rpm. I have about 5 hours of music at that tempo. In fact, here's an interesting database to find music based on its tempo: http://www.cs.ubc.ca/~davet/music/
Now, myself, I would never ever try a session without the music. Whilst the others can witness a guy going very very hard on the machine, from the inside, me, I'm just dancing to the beat. And songs need to be ordered in a way so that the best songs come last. If the order isn't right, I will run out of motivation at the end. I always train at my maximum level over a duration. So if I go for 30min, it's at the highest power output (avg) over the duration. So I must finish hard.
I did also use this extensively in cycling, searching for cadence specific songs (90-100rpm roughly).
How-ev-er... As a spinning instructor (since 2010 now), I was struck to realize that the majority of my classes, just can not follow a beat. They just can not resonate in harmony with it. Of course, we're talking 90rpm+ here, so I donno, it could be normal. But the magnitude of this phenomenon is such, that it got me to conclude that maybe matching tempo isn't at all important for most... I was raised as a drummer, and I'm half black half white. Everything is beat for me.
My spin classes are special, they're for triathlete. Every single week, we have a 25min song, always the same (it's a mix), best possible avg (power) over the duration, and I note the power output every week. People's power output is very dependant on the quality of these mix. If it rocks, power will go up. If it's boring, power is down.
One other area where music truly help, is to manage expectation as to what's coming. Human finds that time goes quicker, when we know what's coming. Going to a place driving for 3 hours for the first time, will feel longer than if you know the road in advance. When you ride outdoor, and you know the path, it's the landscape that does this role. However, indoor, the music can play this role.
Now, you're talking about music / swimming. It may be just me, but I feel that the sound quality isn't good enough yet to transfer this whole concept to swimming. I own a SwimP3 (Finis), but the sound quality is so bad that I can't use it. Thing is that the tone changes depending on if my ears are in the water vs outside the water. That, I can't stand. Therefore, a good old tempo trainer remains the only music I would listen to in the water. And since we're in a fly forum, I think I forgot my TT twice in 2010 (when I was training for fly), and I turned around and canceled the session. I just can not train the fly without a TT.