4 of us in Freedive Toronto ordered Starfins hypers. Here is my review: (My baseline for comparison is a basic Waterways model 2, medium stiffness)
Fit: the back-strap on the footpocket is too big. The foot fits ok, but there is extra length in the strap.
I had asked for :45 mins of comfortable wearing. It is loose, so that I could wear it forever. The looseness causes rubbing on my feet and a loss of power, as the fin moves around and needs to be addressed somehow.
A 3mm sock fills things in, but makes the footbed a bit tight. Maybe 2mm will be fine. I have emailed Alex re: fit and to see if the heel-strap can be shortened. I had wanted it sized for no socks, as it is better hydrodynamics for DYN and less compression for depth / CWT.
Another new Starfins owner was at the pool too an his heel-strap fit a lot tighter than mine. I was jealous.
Buoyancy: I ordered a bit positively buoyant - and it is.
Fin blade action: extremely organic. It looks like an aquatic mammals fin with more bend in the middle and less near the wings.
It loads up really well and almost "springs" to unload. Nice and progressive.
Left / right foot / leg imbalance is really magnified, as compared to the waterways.
Glide: I got 10 more ft of glide on a 2-kick input. I still have to flex my calves to get a good glide, but it is worth it. My speed after 2 kicks is significantly faster.
Because the fin has a 30* angle, I am no longer being "cantilevered" during the glide. With the waterways model 2, I the fin (with legs extended) or my thighs (with legs slightly bent) would pitch my upper body down slightly during the glide. With perfect weighting, I would drift towards the pool bottom in the shallow end. To compensate, I took .5 lbs off of my neckweight. This is no longer needed with the angled Starfins.
Push-off: it is more difficult to push off hard from the wall with the 30* footpocket angle. Any imbalance in the push-off is magnified with more slip-angle, as there is less of a blade-angle to slow you down and straighten you out.
# of kicks:
My previous best (25m) with the Waterways fin was a push off and 3 hard double kicks with a glide to stop. With the Starfins, I was able to do a push off and 2 hard double kicks gliding to a stop.
I was also able to push off and do 4 single kicks easily.
For a "normal" pace, I was previously able to do 25m with a push off and 3.5 double kicks.
With the Starfins, I was able to do 3 double kicks.