Swimming has been a regular part of my exercise routine for a couple of years now. When I injured my knee and most other exercises were off the table, including even the elliptical for a brief period (for a while I refused to accept that my knee was injured and tried to exercise anyway, resulting in an ankle injury on top of the knee injury), swimming was a life saver.
I do not have a problem with overeating after swimming. I plan out my food for the day and that's what I eat; I'm never so hungry after swimming that I need to eat more than what I've planned. In fact, today I went swimming and then to a yoga class afterwards. I was worried I would be hungry after swimming, so I planned for and brought a small snack to eat when I got out of the pool. But I wasn't hungry when I finished my swim, so I didn't even eat my planned snack, much less feel the need to eat anything that wasn't in my plan.
The only problem I've noticed with swimming is that I really have to push myself to get a good workout. When I first started, I had no problem getting my heart rate up, but now that I'm in my best shape cardio-wise, swimming is easy, almost too easy. I include 20 min of intervals in my swim and even those don't seem to get my heart rate up to where it is when I do the rest of my cardio workouts. I haven't worried about it much because I only swim once a week and I consider it to be my "day off" from exercise, but if it were replacing my regular cardio workouts, I'd need to work on increasing the intensity quite a bit. So I would recommend that you pay a little extra attention to how feel on the
perceived exertion scale (which is how I gauge my heart rate; I don't have an HRM) while you are swimming, just to make sure you are getting the same workout you get with your other cardio activities.
Also, you can't compare yourself to Michael Phelps. I can guarantee you that he is doing a lot more than just swimming. He is most certainly strength training and may even be doing other cardio exercise. And he's exercising a whole heck of a lot more more than you're going to be swimming. His swim workouts alone are probably longer and significantly more intense than yours will be. So, yes, he has to eat a lot to maintain that level of exercise (heck, I've read that Lance Armstrong eats 6,000 calories a day when training--no swimming involved), but that doesn't apply to you. You aren't going to have to eat that much to support your swim workouts.
And I'm not sure how much credence I'd give the stuff in that article about increased metabolism after exercise and swimming not having this effect. My understanding is that there are varying opinions as to whether any exercise really increases your metabolism after you are finished exercising unless you are training at the level of a professional athlete (and have the body fat and musculature of one). So swimming may not elevate your metabolism after you finish but it's just as possible that no other exercise does either.