I'd love to try a lunocet. You can haul ass with a monofin if you know how to do it, and the guy in this video most emphatically DOES NOT KNOW HOW TO DO IT. Not even close. He is totally inept, and why lunocet has so many very, very, extremely inept swimmers on their video demos is beyond me.
Top speed with a monofin the last I looked, which was a few years ago, was about 7 knots. The ability to swim 50 meters -- that's a l-o-n-g way!!! -- in about 14 seconds. I can't go that fast by a long shot, but then again, I'm not a competitior. But I'll tell you again -- one can really haul serious ass with a monofin. They are a blast.
Anyhoo, sorry if I got carried away and sounded snippy in my passion for monofinning. Really, it is a blast. I highly recommend it.