pintail diff's ? older to newer designs

Color me skeptical
While the hydraulic skeg is an interesting concept, I’d have to see it in action for some time before I’d buy into it. While it may solve some of the problems with rope and cable skegs, it would be a potential nightmare in terms of field maintenance.

It seems to me that Necky is on the right track with using Nitinol wire instead of cable in their skegs. The downside is that it’s hideously expensive stuff at ~$10/foot, but since a skeg cable is typically only 6-7’ and a nitinol wire has the potential to last the life of the boat, the extra expense is justifiable.