My fin is in customs
I have shimano carbon sole shoes waiting for it...
custom carbon shoes is something on my mind for a while back (even in bi fins context) but I have no access to such shoes or tools to make them. It would be sinful if your friend doesn't try something out
(Please let us know if something comes up!)
I can find a way to cast my feet and send to you ASAP
The main advantage would be comfort... although it's more rigid, since it's the shape of the foot, there are no hot spot as pressure is applied evenly and there's less need for strapping.... also the shoe can be very streamlined
check the
http://www.simmonscyclingshoes.com some wicked looking shoes ($$$$)