Oh, If only things were that straight-forward, sometime after that I discovered there is a load of other unrelated stuff that’s been tagged on the end of the “emonpi” firmware update that doesn’t get done on the “rfm69pi” update. So it would seem users with either a stock emonpi sketch, an edited rfm69pi sketch or an rfm12pi (ie use the emonpi update) get “bonus updates” and those users that have an edited emonpi sketch or stock rfm69pi sketch (ie use the rfm69pi update) do not. (see Update EmonPi Button or Update EmonBase Button? - #15 by pb66 for more info).
I do not think there is anything crucial to miss out on, but none the less it does mean it’s not “exactly the same” and not all update routines are equal (even aside from the FW)