I’d recommend picking a vineyard, Le Mont or Clos du Bourg, buying the lineup, and see for yourself. I’m sure you can find 2017 or 2016 Sec, DS, and 1er Trie.
I normally don’t bother with the straight moelleuxs any more because 1er Trie tends to have more vibrant structure in terms of acids and phenols. As for the other important structural characteristic of the sweet ones, some years 1er trie has botrytis and some not.
Constance is meant to be a botrytis wine, so it has only been made in vintages where there has been deemed to be sufficient ripeness and acidity in botrytized grapes.
Although 1989 Constance is great, you can find the excellent 1995 or very young 2009 at decent pricing last time I checked.
A few of the hard core Huet lovers like me relish the low-to-no botrytis vintages. The 1er Tries from those vintages then get all of the best grapes/barrels — none are siphoned off for Constance.
At all levels the wines will last 50+ year. You would think the sweeter ones longer, but that’s not reality with Huet Vouvray. Old secs and particularly old DS are amazing. And we’ve had moelleux level wines going back to the 1919 le haut lieu moelleux, from before the Huet family bought the estate.
The search function here and on Wine Disorder will reveal a lot of tasting notes.
As for how many people to drink a bottle, it depends how thirsty you are.
In terms of comparison of say 1er trie and Constance with other regions, these wines are better balanced typically than many Sauternes. They blow away all but the best Sauternes IMO. Structurally they are more like Tokaji, but the best way to judge is to try them side by side with dessert wines from other regions.