When Marpat was released and ACU in the process of being worked on, I saw many articles stating the Airforce would use the tiger strip design and just make it a digital outline vs the solid outlines. So I think you are right about the similarity between the two. We need Christian to clarify this. I'm sure he knows more about this than us right now.
The ABU is a pixelated version of Tiger Stripe. There is alot of info on the internet about it.
Jeff, some buddies of mine that are in the Air Force Special Operations community said that, when they are attached to Army units (as a ROMAD, TACP, JTAC, etc), they wear Army Issue ACUs. According to them, they are issued them to blend in with the guys they are supporting. As my buddy "S" put it, "I don't want to get fucking shot at more by Haji because I'm wearing a different uniform."
I see this as "me-too!" politics, plain and simple. At least the Army went with something more functional with the ACU, even if it was derived from the Corps' MARPAT MCCUUs.
As for them blending in to the flightline and aircraft better, I'm calling bullshit. Any AF guy I've ever seen on a flightline has either an orange vest and/or a reflective belt. I cannot think of a case where the tactical situation dictates that Airmen blend in to the aircraft they are working on. I don't think they are trained to use F22s for cover.
Again, just my two cents.