but for the purposes of this discussion it could be concluded that we would not expect any aircraft to ditch, either due to lack of time or lack of crew decision.
I don't think we can rule this out, alf - as I hinted, in ETOPS it would be the only option. Both time and 'crew decision' would allow.
Put crudely, there would be no more time and no other decision.
I am very uneasy at the lack of fire-fighting equipment on board modern a/c. I do not know about ETOPS, but does the extinguisher requirement leap dramatically?