One Green World lists all three of the cultivars I have, although I actually got them from Jung's at the time.

Here is a link that might be useful: Edible Mt. Ash at One Green World

edible, but maybe not palatable. Both of my Ivan's have fruited, I don't recall any wow factor and the berries seem to disappear too soon, so don't get to test the frost idea.

I'm always interested in these, think I have Rabina or Rosina,..funny, my daughters name is Rosina. I guess it's similar as the sea berry, on it's own it's not very good.
I grafted the edible mountain ash about 5 years ago to a ornamental tree, two branches, had fruits for about 3 years, last year I juiced it and blended it into the apple juice, it was very pleasantly spiced! This year, for some reason both branches started out good, flowered with some berries, then both branches died out, the rest of the tree looks fine. I now have to start from scratch!
The worst part of all, nobody sells this one in Canada..as far as I know. I will miss this one!

I had an Ivan's Belle and an Ivan's Beauty...wasn't impressed with the fruit. So unimpressed I got rid of them. I wanted to use the space to grow something that tasted good.

I never thought of blending the berries into apple juice. Sounds good. Wish I'd been reading this forum back then.

Well, I boiled my little handful of fruit, extracted the juice, and cooked it down with some sugar into about a third of a cup of jelly. Its actually not bad at all, flavor is very similar to cranberry. It does have a bit of bitter aftertaste, not inedible but noticeable, and I think that mixing it with another juice like apple or white grape would be the key to fixing that problem. The color of the juice is a beautiful ruby color. So, they do have some use, imho.

Even if they weren't edible, the trees are going to be very pretty.

Berry suppose to eat after frost, it's change taste. Some of berry leave on tree - birds love it. Made vine, put berry in vodka.