Great dinner, Bill!
My comments on the wines:
Ch. de Mosny Montlouis: not a good way to start off, arguing with one's host, but I completely disagree. I much preferred the older wine, and found it had greater and more satisfying complexity on both the nose and the palate where the new wine was dominated by residual sugar and needed time for that to integrate.
1979 Sassicaia – The nose was initially iodine and mint and reminded me of some Central California pinots I've had about 8-10 years out. My first thought was that this was in fact what the wine was, and the other, which was more balanced but had less fruit in the finish, a Burgundy. But I didn't stay with that thought long, as the pair quickly developed a more Bordeauxish profile without the heft one would have generally expected from a Bordeaux. Throughout it's life in front of us (and paired with your fantastic mushroom course), it was the lesser of the two wines. But I did save a bit of each which I went back to at the end of the night, and that exercise was surprising; the 82 had faded where this 79 still had something very nice to show.
1982 Sassicaia – As you say, darker colour, younger overall (seemed more than three years compared to its flightmate) with excellent balance. A very classy with with very obvious finesse. You spoiled us!
1994 Umani Ronchi Pelago – This pair was much easier to pick out as Italian than the Sassicaia, we didn't guess anything else. But after that, and identifying the cabernet and merlot, it was impossible to pin down. I can't improve on your description, except to add that it was my favorite wine of the night.
1995 Umani Ronchi Pelago – Again, can't improve on your description.
The cheese-off: The Stilton was Stilton, which I love, and it was good. But the Stitchelton was in a whole different league than the Stilton. Beyond the creaminess, it had that nutty sweet thing going on, almost a nougat kind of taste, that was totally captivating. I've never had anything like it. Worth seeking high and low for, for those who have access to such things.
1987 Cockburn’s Quinta do Tua – This was superb. I had to fight to keep from asking for seconds, lest I wake up with one of those dreaded port headaches, but I liked it enough to make that a struggle. It was very definitely the quality of a top house in a declared vintage and I'm glad you shared it. I don't have much experience with single quintas--we don't see very many of them around in the U.S.