I have najade speed and sprint fins and now iron fins, they are faster than the other models but could be made a little longer then they would be world class.
I have tried them upside down and they are faster but uncomfortable to wear. Why not make them upside down with the foot pocket the right way up?
I have been playing underwater hockey for 27 years and used most fins on the market.
speed, manoeuvrability , comfort and safety.
nadjade fins have it all , just lacking a bit of speed.