My experience is that pluots in general do taste better than J plums. I started out with many of each in my greenhouse and over about 5-8 yrs all the plums were let go and a half dozen pluots survived because they are sweeter and more flavorful. But that’s under ideal conditions with a CA like climate and full water control.
It’s about like the comparison of peaches and nectarines. Nectarines like pluots are harder to grow. But as the recent thread Nectarines just better points out many people agree that nectarines are better than peaches even out East.
It takes a lot of yrs tasting a lot of fruit to say with any authority that one class of fruit is better than another. Like I say it took me 5-8 yrs to decide and that’s with a good crop every yr no rot or squirrels. Also culture has more effect than cultivar or species. A well grown plum will be better than a watered down pluot regardless of cultivar. Out East may be different than in a dry climate like mine.
That doesn’t mean pluots are a good choice for the SE. Even spraying the best materials it will be a battle with rot and more.