I'm also a Forza fan, but I never really considered either Forza or Dirt 2 simulators. Dirt 2 always seemed like more of an arcade style racer. Either way, you're missing out if you're not playing with a wheel. Dirt with a wheel is pretty difficult.

 

after seeing the videos of the gymkhana, i have not much hope for dirt 3

UNLESS they just alter physics for the gymkhana portion of the game, much like games altering physics for drifting.