I would most certainly use it. I would have also loved to use Kodachrome 400. I really wish that Kodak had put out just a few advertisements in a couple of magazines in the later 1990s. I found out about Kodachrome as a kid from seeing it in old National Geographic magazine ads. If some advertisement from 40 or 50 years ago sold me on a product, imagine what new advertising would do to stir up interest in young people that never heard of Kodachrome. I am shocked to meet photographers in their 30s from different parts of the world who never heard of Kodachrome. I remember all of those advertisements for that horrible APS film and system...if only a fraction of the money spent on that was spent on Kodachrome ads...well, I would have most likely started to use Kodachrome at a younger age.
Haha, everyone remembers Joe Camel...why was not there a Kodachrome Kid? Ingraining a product into a child's mind before they are old enough to make their own decisions can be an effective form of advertising.
Anyway, 120 Kodachrome 64 for my RB67 would make me extremely happy.