I'm often using very old film; one of my all-time favorites is some Ektachrome Prof 64; I have some that expired in '81 and some that expired in '84; frozen since then (except while being mailed to me). I shoot it as 80 and get great results - very very nice browns, purples, blues pretty good too especially medium blues; whites, grays, not so handsome (but not magenta or anything bad, just not amazing), greens OK if there are browns and blues/purples to balance the scene, but a little grayish or dark. In other words, great spring colors film, but i don't use it in winter in Alaska so much where the colors are gray, white, dark gray-green (spruce trees in winter), etc.
So the film has changed; not into something bad or unrealistic looking, but to something that looks incredible for some types of light, and not so perfect for others (like all film). My advice would be to test the various films under different conditions (lighting, colors, speeds, etc.), maybe get a test patch and shoot it to compare to the results, and then decide if you like the results, and for what types of shooting. If some colors don't look as good as others, think of situations where you could take advantage of the colors that look good. Of course if it's too far off then there might not be much to use it for except 'weird' shots (night? high color shots? abstracts).
I consider my early '80s EPR64 to be one of the greatest film 'finds' ever, and will miss being able to use it in leafy spring deciduous woods when I have shot the last roll (I have about 8-10 left I think). People can go on an on about kodachrome, or portra, or ektar, or HP5 (I do), because of their great colors or grain or lack of grain for whatever use and the amazing palette unlike anything else, but how many people out there have gotten to use my 'secret EPR64 emulsion'?
Have also shot a fair amount of KR64 from same source, expiry 1984, 1986, 1987 - also good, but i don't see a palette change so much from the original in those (of course kodachrome's great as is). I also have some vericolor III, same source, but haven't used it much except to verify that it's still +- good; haven't printed or scanned anything to tell further.
I just test developed one roll of Soviet 'Svema' 64 B/W film for a friend last night; he shot it in '94 and it's been in closets of fridges ever since... Developed normally in HC110 and it came out apparently normal (maybe very slightly lowered contrast, but the film wasn't very high contrast to begin with); entireely adequate. I have about another 20 rolls of his vintage '92-'94 to develop yet ... time capsules!
