Could be I'm missing something in all this, 'Which came first, the down or the (flight) feathers?' controversy; but as a simple neophyte in all this, it seems to me certain persons have forgotten a long-held axiom of comparative anatomy: ONTOGENY RECAPITULATES PHYLOGENY.
In regard of this, if flight feathers came first (from scales or however), then how is it that all the hundreds of baby chicks I ever watched in a farm town while growing up in south Texas always hatched with 'DOWN FEATHERS' as the first covering, only after which appeared the 'FLIGHT FEATHERS'?
O.K., so maybe south - Texas chicks are some kind of mutant freaks and their ontogeny doesn't recapitulate their phylogeny as do more 'normal' (less mixed-up) chicks?
Whatever, all those hatchling chicks seemed to do pretty well with only those 'maladaptive' down feathers, unaware that nature had done them wrong!
Maybe some theorists should spend a bit more time observing what nature has accomplished, and how it happens chronologically. Ontogeny's recapitulation of phylogeny can be a powerful window into evolution, if our intellectual horse posteriors are made to follow instead of lead.
Bet this stirs up both down and flight feathers, whichever came first!