The "premium" over rFactor isn't worth it. Besides, with some of the new(er) suspension/physics building tools available for rFactor, some of the newer and up and coming mods are going to be scary good.

One HUGE turn-off for me with iRacing, is ZERO offline play. A huge draw for me with rFactor is I can load up any one of the top mods and just go bang out laps to my heart's desire. Whether I want to tweak a setup, or just drive...it's always there.