as you probably know by now, split fins use diffenty physics to create thrust than old-fashioned paddle fins. paddle fins create thrust through the displacement of water on the down stroke only. however, paddle fins push water in more than one direction, wasting energy, and also create drag when no on the down stroke. if efficiency and speed are what you want (and you don't mind paying an arm and a leg), spring fins are the answer. they operate through the same principle as paddle fins, but remove some of the surface area of the fin, and support the blade with springs attached directly to the foot pocket. i use a pair of these YouTube - SCUBAPRO Seawing Nova Fins but the best advuce would be to make sure your kick as efficient-as-possible first. remember that short, quick kicking waste's energy, and to use long powerful kicks. try having your dive buddy film your kick from behind ... i promise you you're not kicking as wide as you think you are!
not true, not even close to true, splits=paddles that is the fact, splits just move less water than solid paddles with each kick allowing a high kick frequency. the Nova's are just old school paddles that are trying their best to emulate a ForceFin.