My DC14 has both a removable rudder system as well as a removable fin system. The intention here was to have the best of both worlds. It proved to be a bit of an overkill for me, however, as I don't do much racing so I hardly ever use the fixed fin system. Still, it is there is I ever need it.
Here is a picture of my early fin system but I do tape up the fin hole when I am not using it.