My question is: do the full-array LED sets have considerably better picture quality than the edge-lit ones? Are edge-lit LEDs on their way out?

But things get interesting when contrasting between full-array local dimming (FALD), direct-lit (DL) and edge-lit (EL) LCD TVs.

Edge lit LED-LCD screens are often less uniform. Backlight bleeding (blooming) is set dependant. You can get good and bad examples of the same model.

So just because you get mini-LED doesn’t mean you give up on full-array local dimming. It just means the led backlights are smaller, and there are more of them.