I recently shot some old Kodak PR-100 220 rolls. I was very surprised that they came out with colors as good as (absolutely no worse than) the Konica (Konica Minolta) not old (frozen when it was still fresh) KN-400 that I also shot. The interesting thing is the PR-100 rolls had been left in my backpack for 2 years unattended. I guess I took the pack out of the freezer and then left it in the backpack totally forgot about it. I actually thought they had practically gone beyond usefulness even for snap shots. They came out beautifully.
I just looked at the PR-100 box and the expiration date was in 1999. The KN-400 had been frozen since 2006 with the expiration date of 2008. Konica KN-400 is a great film. The old Kodak Pro-100 after all the years in the freezer with 2 years left in the backpack turns out to be as good or better. I believe the films were already expired when I bought them on eBay. I still have a few 5-rool packs. The only hassle to use these films is I have to use Kodak Stabilizer which is no longer available. These films (KN400 and Pro-100) is a solid proof to me that their colors are superior to the digital camera images I got from my 17 mega pixel Canon for dummies. I now use the Canon only when I need to sell something on eBay.
By the way I processed theses films by myself with my Jobo ATL-2300. I believe the processing is a significant factor that the films came out so great. I have finally figured out how to use the Jobo correctly. I used only 470 ml of Kodak C-41 developer for 2 rolls of 220.