This fantastic link was posted just a bit ago:

http://rilezu.com/

I repost it in case you missed it, since I'm not 
sure where else it can be looked up. (I didn't 
know it even existed until I saw it here.)

As far as size. . . As I understand (anyone feel 
free to correct me), post-production cels are the 
same size as they would be if the scene had been 
made with cels. Meaning, a standard sized cel is 
the same standard sized as a production cel, and 
a pan frame is bigger, etc.

It's too early to decide how sought after they 
are. Some people seem to like them, and I've seen 
quite a few marked as sold when I look at sites 
selling them -- someone is buying them. But it 
seems you simply don't hear as much about them as 
production cels. But again, they're fairly new on 
the cel collecting scene. I'm curious about them, 
although nothing has yet tempted me to buy one.

Many Sharp Smiles,
--Drac