I'm not sure about others, but for me single kick and glide is pretty much how we all started diving. The reasoning was that if you want to go far, then you want to glide as far as possible.
After Peter Petersen's record the trend was continuous kicking. The reasoning behind that was that it takes less energy to maintain movement than to come to an almost halt and start again. With kick and glide you needed one explosive kick (and it was very hard to do with old fins without slipping sideways etc) but with continuous swim, you could maintain a constant, relaxed speed with little effort. So for a while we all did that and results improved (by we I mean me and people around me). At the time the "stars" were Peter, Stig, Alexey etc and all (at least as far as I could tell) were using this style at the time.
When I first heard about Henning passing 200m, I thought that naturally, being a Dane, he must be diving a similar way. But when I saw the video it was very surprising. That was the mother of all kick-n-glides I had ever seen. With a really explosive one kick, then a long, long glide almost to a halt. Exactly the thing that I had just convinced my self was not optimal. Well ok, different styles suit different people...But then also Peter and Stig started doing it so I figure there must be something behind the idea - other wise they would not abandon an already good style I recon. Unfortunately before now I had never the pleasure of seeing Ant or Walter swimming.
For me the single, explosive kick did not work very well. I find putting enough power to one kick to be quite excerting. But I think this double kick might work pretty well for my style so certainly I'll give it a try.
Well, what have we learned? So many different styles, fins (monos, bi-fins), materials...so many impressive results...I believe there is no single "absolutely right" style. It all depends in so many things. Personally I like trying a lot of things and also having a big "bag of tricks". For one to keep things interesting and also to be able to adapt to different circumstances (for example I know now a pretty good mouthfill, but for the heck of it I often dive with negative packing frenzel to keep in touch with that because mouthfill in very cold water is next to impossible because the lips get numbed)
Nice to see new things and have something to play with. But I would urge anyone not to fall into the trap of thinking "longest swim must equal the only good style". It is so very much more complicated than that
By the way - has anyone tried swimming dyn with CNF technique, but using paddles or something? Would that be allowed by the rules if you consider the paddles "fins"?
Or doing a monofin kick-glide-handstroke-glide...Something like that (it's fun at least, if not impressive in results)