Mattpf:

I do not personally grow Pipestone plum. However when I lived in Minnesota, I got some free from a friend. I thought the size of the plum was large compared to other varieties grown in Minnesota. I found the flavor to be a bit mellow. Since I only had them once, it was not a fair judgement on the flavor.

I can tell you that I was very partial to Underwood for flavor although nobody seems to offer this variety anymore. The fruit was somewhat small and the skin is a bit tough but I thought the flavor was fantastic.

Superior is another one that seems to have a cult following on flavor. A friend of mine who grew many plums at his u-pick orchard claimed this one is the best for plum jam out of all the cold hardy varieties he grew. Personally it was not my favorite on flavor but flavor is something different for everyone. Hard to judge what someone prefers in flavor.

I did find Alderman to be an awful plum on flavor. Again perhaps just me but I did not even eat all the one's I once purchased at a roadside stand. Very juicy and good skin color but no flavor at all.

They possibly were not left on the tree long enough

Just had my first pipestone plum today. and I thought it was the best plum i have ever eaten tasted kinda like bubblegum flavor.