These days I'm almost only flying the 1a exclusively, unless I need to drag a lot of ord to the field, then the 1D is my mount.
Actually, the fuel arrangement is one of the things I like best about the 1a. In a 1c or 1d, you only have one fuel tank. Take a bullet in your one fuel tank, you're basically a dead duck. (I know, climb like heck on WEP, pick up some speed, and hope to glide 'er back in, but you can't count on that climbout in a furball.)
The 1 and 1a have three fuel tanks: 1 main and two wing tanks. A bullet in any one of them leaves you with plenty to fight some more, and then cruise home. At least, if you don't burn off the wing tanks immediately.
Nothing's worse than having an otherwise perfect plane with a bullet hole in your fuel tank. Unless you have two others...
-Llama