I play IG too. Maybe it's just my meta, but the power differences between codexes seemed to shrink.
Have you played against a dual skyhammer or eldar or necron or any of the crazy quad
CAD list people sometimes post? But truth be told I have problems even with casual stuff. I still don't know how to deal with a tri NDK or dual ndk with centstar list in a mealstorm enviroment.