Is it worth the cost is really up to you. Where and how you fish. I have not demoed your kayak so no information there and each kayak will respond different not to mention the different style rudder blades you can get. Some kayaks will blow like a leaf and some turn like cargo ship. On a shorter kayak it will help with tracking mostly. The zigzag motion your kayak gets from paddling and they can make it more efficient. A skeg (non-turning rudder which acts like an extension of your keel) will do the same thing but make it harder to turn. It is nice to glide and change directions with out a paddle in the water.
Longer than 12' will usually track fine so a rudder is used more for turning. It's Harder to turn if you have 7' of kayak in front of you verses 5' or less. Twelve's or less can turn easy in tight places so not much improvement for you there. Honestly I paddle a lot without one and do fine but once you use them for a while you rather have it.
I guess if I had a rudder to fail I would just keep paddling
. My oldest rudder setup has been on since 2005 and not a single issue. My second oldest since 2012. It's still going strong and it got rear ended. Never even thought that my rudder could fail when I'm on the water
. As for drag I forget if mine is up or down. Couldn't even tell you if it was up or down unless I tried to turn with it or looked at my control. It's a thin blade and unless it's turning there is no drag.