It kinda bugs me when people grow an inedible or poor-tasting plant in lieu of an edible one for which there is almost no difference. In your case, bad tasting natal plums. Up here in Iceland the one that always gets me are the Ribes sp. hedge rows some people plant, both on public and private property. The bushes look just like redcurrants, the berries look just like redcurrants, it's a sister species to the redcurrant, redcurrants grow just as well up here.... except that the version that they plant tastes vile and disgusting. Why, I mean, why? If it makes no difference, why not have something that actually *tastes good*, even if you don't plan to pick it yourself?
I've had to learn to recognize the small difference in the leaves on the vile tasting ones when picking berries on public property. :Þ