The P8 argument is completely irrelevant as it was not In the procurement equation and therefore irrelevant to the boom v drogue argument.
Up to a point. I wouldn't say that it is
completely irrelevant, as it would have been known that receptacle-equipped aircraft existed and that there was a chance that the RAF would at some point over the 27-year FSTA private finance agreement perhaps acquire and need to refuel such equipped platforms (if not the P-8 and RC-135, then certainly the C-17 and the Voyager itself)
What are the 5 large aircraft you refer to? I can only think of P8, Rivet-joint and C-17, I don't include Voyager in this as its not really a requirement! The Hercules, A400 and Sentry all use drogue.
I
would include the Voyager, as with AAR it could at least get to the Falklands in one-hop. Not a 'requirement' perhaps, but potentially useful, and why not have the capability to do that if it exists?
The Sentry uses both methods, though it is my understanding that it uses the boom from USAF tankers more often than it uses the hose. I stand ready to be corrected on that though...