Can anybody tell me if there is any truth to the idea that fitting an AU head gasket to an EF/EL it helps solve the blown head gasket issue with the E series falcons?

you have a PM

Welcome to the forum.

At the top of this workshop you will see a sticky that has the answer to most of the commonly asked questions (including this one). It is worthwhile have a quick look in there first.

And to answer you question, yes the AU gasket is stronger, but you must have a flat deck on the block and get the head skimmed. If the surfaces arent flat the AU gasket wont seal.