WTF - I'll stirr the pot I have a +4" arm and I dune the ever loving shit out of the thing, jump the shit out of it, do a little bit of hill shooting / drag racing with it too, and love it! I went from a stock length arm to the +4, never ran a shorter than stock arm, and have no desire to do so ....Keep in mind that rear suspension set up has a LOT do do with how well the arm reacts to launching and traction. Those of you who run a shorter arm and still run the stock spring are increasing the wheel rate (less leverage on the arm acting on the spring = smaller motion ratio) The oposite is true for those of you with a longer arm and the stock rear spring (decreased wheel rate due to more leverage on the spring = larger motion ratio)
EDIT: Here's my +4