... in my opinion is more to show the ability to achieve such color. Such black enamel dial for this 3939pt, is more likely client's preference. Regarding the differeneces, i certainly believe enamel dial will age better than lacquer. The fun thing about enamel dial with the air pockets you described, shows the difference, the inperfection of having enamel instead of lacquered. I still dont understand the demand for black color dials, other than manufacturer make less of them, whereby created a higher demand within the exclusive world of collectors.
Enamel dial has a hidden danger, which lacquered will never have, it doesnt crack. I do agree, should one choose enamel, stick to white instead of black. Somehow, black looks cool on picture, but not on actual. But im sure there are exceptions.