I've received quite a few notes and comments about expired film. First, where to get it. And second, how does it play out at the lab.
I hang out on eBay when it's time to stock up. There are a number of sellers there who have a substantial inventory ranging from current expiration dates to 10 years old.
I usually buy 4-10 rolls, test one of them, then note its characteristics so I'll have a reference for shooting the others. Generally speaking, the results have been really good.
When I have the film processed and scanned, I do add a note to the order asking for minimal corrections. Some basic corrections come with the scanning process itself. But it's the additional ones I want to avoid, and a note to accompany the film seems to do the trick. I've never had as lab ask me if my film was expired. They just process it along with the others of the same type.
To be honest, when I first started experimenting with this type of stock, I thought the results would be more exaggerated. But for the most part, they haven't. (Just really good!) So the biggest benefit has been paying $2-$3 a roll instead of $8-$10. And I definitely like that.