There would be some interest if Microscale or others no longer make the same decals. Also, Champ made some decals that no one else made.
As for as usability, I asked this question here back in April ……. USING CHAMP DECALS . The hobby shop I purchased them from even included instructions stating that some sort of clear coating …. before soaking them in water …. MAY be necessary.
I have not tried to use them yet, as Atlas has not shipped my engines.