Oh, one more thing: It is a little impossible to "let people try them" BEFORE funding the manufacturing to actually make them. It is not reasonable to run a large scale demo with rediculously expensive one-off prototypes.
We're sure they will be the next best thing since sliced bread and will cost less than my closeout accels and come with warmed-up slippers in the morning when they come. In the meantime the OP is looking for a pair of fins that don't hurt the ankles and don't tire out the legs. The useful advice would be to actually and figure out why those things happen, then what to do about it.
I mean, realistically, the price point for all those one-off patent-pending handmade superfins is such that you can add a nickel and buy a scooter. Leg problem solved.