The first fin I used was a Mat mas, just a basic one but it did have an angle below the footpockets so it was pretty decent. The material was good, a mix of carbon and kevlar. Nice and snappy. It was a relatively soft fin. The footpockets were comfortable but they seemed to stretch over time, more than the waterway ones did. Also the blade was a fair bit larger than a waterway fin. However my memory of the fin isn't so good and I was just starting out so wasn't in a good position to evaluate it properly
I think Giacomo De Mola was using a fin very similar to the Evolution Freediver in Egypt last year. I don't know what stiffness it was on the Mat mas scale, but it was very soft - softer than the waterway LD for instance. He had built up a rubber wedge under the footpockets to give the fin more angle.
Not very detailed or reliable information, but the best I can do. I just don't think many freedivers are using mat-mas monos for some reason.
