Mostly I think rudders are very handy. Especially when I'm sailing or paddling with a single blade. But they break in the surf and they are a hassle in shallow rocky rivers or weedy areas. I don't want it for turning the boat I just want it to work as a trim tab. Mostly they work great, but I'd like one that did not break.
In my quest for a better rudder for my Cobra Expedition. I have taken a page from Mirage kayaks and fashioned a lower aspect rudder with a much longer cord length. It always stays down and is very strong. It is a flat plate so there is too much drag. Maybe I can have someone make a thicker one and shape it like a foil for less drag.
I think the ideal one might be very close to what Mirage has already done. I wonder if they make any boats out of plastic or that are Sit on Tops since that is the type of boat I like most these days.