There seems to be a consensus building here...
Longfins are longfins, and you can't learn anything about KOI from a longfin.
Wrong body conformation, wrong fins, wrong skin (hybridized skin not the same as a similar KOI).
We have ONE longfin because my DW loves 'em. It adds it's own flair to the pond, but it is not a Koi and never will be. We bred it to an orenji just to have some longfin ogons for next years club auction 'cause wger's love 'em. Otherwise, they're just a fish taking up valuable space in a KOI pond.