This has no doubt been brought up before, but not in the forum as far as I can see. So,
I think it was Nick Park who said that mouth movements make up only 15% of a character's expressions. But it is always a big deal and takes a lot of time, and having mouth replacements seems to be the most common and popular technique. But then you have guys like Dino Stamatopoulos, who made Moral Orel and Frankenhole, who handled lip sync in ways that look relatively simple and time-saving:
http://www.youtube.com/watch?v=ZyP3JY7yKvw Moral Orel: Mouths like stickers or added digitally?
http://www.youtube.com/watch?v=XMZNAaxnGls Frankenhole: Moving cardboard chin and a tongue when necessary
Especially Frankenhole is creative and original, too. And I assume they wouldn't have been able to make so much of those series if they had clay replacements to do the job. But if you want to be realistic, I guess such a solution would be impossible.
So do you agree with Nick Park, or would you simplify lip sync if you had to prioritize your time/budget? Do you know of other unorthodox lip sync methods that you like?
Right now I'm lip syncing with just plasticine, a reference sheet and a mirror. And thank you all for the wonderful thoughtful responses I get when asking things here.