Hi,
Given your location, I would think almost any of my varieties would do very well there in VT. Perhaps a bit shorter growing season, but most of mine have ripened by late Aug. Of the ones you listed I have
Black Ice, grafts which have not yet fruited for me.
Alderman, same as Black Ice.
Lavina: Definitely worth growing
Superior: Do not have yet.
Methley: I hear a lot about others claiming it’s a black knot magnet, but here it’s one of my best Asian pollinators, fruit is very prolific and good fresh eaten.
Stanley: Along with Empress are our two best high quality European plums.
Santa Rosa: No black knot here but the fruit is sub par, so I am over grafting mine.
The above thread are my current fruiting varieties this year.
I would rate Luisa and Sweet Treat as our top Asian and Stanley and Empress as our European winners! Most likely those would do well for you.
This past year I grafted a large number of new hybids and new natives from northern growers to improve my cross pollination here, so next year some new ones should fruit for me.
Best wishes
Dennis
Kent, Wa