Ahh, the classic "what if" about the Merlins
I love those. The P-38 and Whirlwinds would probably have been classics (though whether the Whirlwind would have been continued if the P-38 had been pressed into service is open to debate).
But alas, the Merlin being the precious commodity that it was, we'll never know. If I ever won the Euro Lottery (I think the domestic standard lottery win wouldn't be enough) I'd love to commission a Whirlwind, and actually use Merlins - and see what the critics have to say about the aircraft then.
Thanks for the update, Andy.