You got it right - get another fin. Hopefully Starboard will find a better fin design for their futuras and iSonics in the future. Sanding the Drakes helps, but only a little. I have a Techtonics fin on my iS 111 and it is a 100 times better than the Drakes.
I doubt that anyone uses the Drakes. Why not cut the price of the boards and skip the fins, or at least come up with one decent fin?
Conceptually, the two fin plan for the iS boards is great, Starboard just hasn't found the right fin yet.
Just think of all the money spent on fins that are just sitting in boxes somewhere rather on the back of boards. Such a waste.