I would think that a brand new, modern, multi-billion dollar computer designed airliner that has been shaken down for the last 30 years would stand a better chance of surviving in that environment than a bodged up comet? Plus the maintenance is very well understood, spare parts available off the shelf, worldwide, huge manufacturer support etc... I don't believe the comet was ever designed to be operated low level across the ocean either?
It's time we learn from our mistakes, flogging the VC10 & Tristars on for as long as we did led to serious operational performance problems, not only from a (hideous) reliability point of view, but supporting the aircraft worldwide with no real back up from the manufacturers etc.. Operating a modified civil airliner has huge benefits that vastly outweigh any downsides. Funnily enough, all of the old sweats crowing about how the A330 was vastly inferior to the old Vickers funbus & deathstars have gone very quiet.
The Operators, Engineers, Passengers, Receivers all love the MRTT, because it turns up, does its job & goes home..... There is a lesson in there somewhere?
Besides, the venerable 73' has looked after numerous lo-co sausage factory first officers, including "that" Irish Airline, I'm sure the Raf couldn't be much heavier on it!