I was curious if there were any dedicated breeders of Cochins on this thread that were trying to restore this breed to its original genetics of being an excellent dual purpose bird known for meat and egg production?
I have actually wondered this myself on occasion. I have some standard cochins, though they are mixed colors from project birds I ordered a couple years ago, and I don't show, so I can only make a guess at their type based on looking at pictures of other cochins and try to keep working in that direction. I mainly keep them because I think cochins are gorgeous birds and like their overall temperaments (except for one hateful rooster so far). I don't really plan on showing, but I would like to try and breed mine to make them look closer to the standard. However, I'd like them to still be decent layers (as I mainly sell extra eggs from my chickens to help pay for their upkeep), so I find your question very interesting. Out of several breeds I've had, cochins are in my top 3. However, they do have some issues at the moment as dual purpose birds.
My cochins lay fairly well when they're laying; mine tend to lay in the fall, winter, and early spring. Then, in the summer, they start slacking off the laying and start going broody. I had one that stayed broody nearly all summer; even when I put her in a pen with no nest box, she just started setting on the ground. lol. They're very determined about it, too. I think just about all my cochin hens tried to go broody at least once last summer. I divided some eggs between several of them, and they seemed satisfied with that.
As for their meat properties, I have only eaten one cochin so far, but the taste was fine, better than store bought, but probably not as good as some of the more typical birds used for meat. I used a crock pot, so the meat wasn't tough either. I may end up eating more eventually because I know if I hatch out more, I'll most likely wind up with some more roosters in there, and right now, I have 4 cochin roosters.
I still think type is important, though, because it still needs to look like a cochin. I know that some of the show quality cochins' feathers have to be trimmed so they're fertile. I think that's a bit more fluff than I may want personally. I like them to be able to reproduce without human intervention. However, for show, the fluffier, the better, so that's something that needs to be taken into account.
I think that it's possible to get cochins to the point where they are excellent dual-purpose birds and still look the way they're supposed to, but it will take a lot of work. It seems like it would be a very, very slow process to improve the other qualities while still keeping the type intact, but I don't think it's impossible. If it was impossible, the breed would've never existed in the first place with the qualities you mentioned, and other dual-purpose breeds have improved in areas like this without losing their aesthetic qualities. I'm not sure how one could go about improving their laying qualities honestly; I wouldn't really want to outcross them to a different breed because that would really affect type (mine are probably not show quality anyway), so maybe pick your best looking birds and breed them to some hatchery cochins, which generally lay more. My idea was to maybe try breeding my best egg laying cochins and see if their offspring also inherit that trait. It's definitely an interesting proposition.