there are other sutleties as well - with the fm2 your turn radius out of the box is very tight - you don't have to pull heavy g's to get a tight turn. spits in general can stay airborne and maneuverable while slow, but the fm2's tight radius is a natural advantage. the spitty guys may also be working the vertical to keep your nose up, slowing you down-- spits can hang hang while going slow, or can keep their nose up while turning tight. I love both the fm2 and spits, but i'd say the fm2 burns its e quicker. watch your spitty opponents and see what they are doing when you start feeling that you are losing the fight. and fly the spit some to figure out what it can and can't do. spit 5's are more of a problem in a tight fight; heck hurricanes as well.
I believe you said your stick has a twisty rudder - they are typically twitchy compared to pedals, so make sure you scale your rudder to make control inputs controlled, not violent.