No, the installations may be different and the failure modes possibly, but unlikely. But IFF Mode 4 is IFF Mode 4. I've used it in three jets US and UK and it's pretty much the same fish. The failure modes he's describing chime with my recolection of the facts. We're not trying to second guess a BoI here, we would (generally) be foolish to try. So I'm not sure what your point is.