I have found that most race type boards track very well due to the rail shape, bottom shape.. and board outline and tail shape.. and it's often turning them that's hard work.. so moving the fin forward helps some.. If you have a board that doesn't track well then moving the fin back will help.
I'm not a fan of the dagger style fins unless they have some curve in the end (like the JM fins) because they tend to dig in and catch if they touch.. even in soft sand.. I'd also keep away from deep fins or fins with heaps of rake unless you have seaweed issues.
I think the dolphins got it right..

.. btw.. I would not call the new Fanatic fin an 'axe head' shape fin.
I don't claim to be an expert on all this.. It's just my own thoughts and I'd love to hear what others think.. Here's a pic of the JM fin.
DJ