I got mine to fit my drysuit boots (a bit tight) and still use them with a thick wetsuit boot (a bit lose) about 2.5 yrs ago because of the price point when they first came out. And of course I added spring straps.
I have really given them a beating. They are light weight on my reconstructed ankle which was important but powerful enough to get through a current (I had been using splits but was stuggling in cold SoCal currents with so much drag/gear on).
I mostly frog kick but when I do flutter, they sometimes ricochet/reverberate back after the kick and I can hear a noisy whoosh. This has become much more noticeable as they get older. I have also noticed the blades have begun to warp/cup from center outward. I will continue to use/abuse them.
However, I'm now in search of/testing new fins, especially since I no longer work for a SP dealer, I'm supposed to teach using store brands.