There's another place we disagree, TL. I prefer to buy younger, smaller fish when both adults & juveniles are available. It may be that my experiences with both species was before both were heavily farmed...& that can make a huge difference!
Neons are often listed as being in the same habitat as angels, mid to upper 70s, but not cardinals. They're from shallower, warmer water...like discus. I know that's comparing farmed vs wild caught fish, so may not apply as much anymore. It depends on where they are farmed too. It's not that fish can't survive the "wrong temp" & as you've seen, farmed fish are more adaptable for the most part. But if I had hard tap water, I'd opt for Fla. bred fish; if I had (as I have now) softer water, I'd go with Asian bred fish...IF I knew where the fish came from at my lfs...That's not always available info.