In the case of serotina, I can’t help but wonder if the fact that many phenotypes have the potential to form a ~80ft tall 3ft + diameter tree might be slightly problematic when used at rootstock. I have seen dwarf forms growing in secondary dunes on the Atlantic shoreline here in the northeast, though I’m not sure that their forms reflects unique genetics or, more likely is just a result of severe site conditions- salt, wind, drought, lack of N or many available nutrients.
I think @clarkinks and others, myself included, were sort of riffing on the potential for improvement, given that as wild foods go, black cherries are already sorta pretty good.