I’ve had a few Prunus ilicifolia fruits, and had a similar experience. They were mild, but pleasant, with subtle sugar and very little flesh. So much so, they seemed pointless to grow for fruit, unless you had a passion for breeding, and 30 years to spend on the species. Haha… Maybe a cross could be made to make a more desirable fruit?
In regards to Prunus salicifolia, I have only tasted Emerich #1, which was pretty good. If I’m remembering correctly, even slightly underripe fruit was pretty astringent and unpleasant. A little funky tasting. Not much margin for error in picking good fruit. However, the perfectly ripe fruit were delicious. They were slightly smaller than sweet cherries, but had a good flesh to seed ratio.
I probably had 200 flowers on my 5’ tree, so I’m suspicious it need a pollinator.