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An additional risk is that for November, a lot of things can change including flights being retimed or cancelled, so booking now could mean either of the two itineraries being affected without the other becoming flexible.
I'd recommend the OP has a look at the b2b thread - DUB is by no means surefire now, and even though the new terminal theoretically has a connection route, it also comes with greater risk of bus gates. Bus gates are the no1 enemy of b2b plans because if the arrival flight is delayed, the airline may well choose to board people on time and put them in buses to try and recoup some of the delay whilst the arriving passengers may have been significantly delayed and waiting for half the plane to fill the first bus.
So personally, if that is the timing of the departure flight, I wouldn't consider either option fully safe given the risk of losing an expensive long haul J trip and would come the night before.