Alan, thanks again for doing this 1-year test. Frankly, I'm surprised it did that well considering how orange it's become. I guess it's more robust than I thought. Even yellowing was making me concerned, but orange? My current formula is similar to D-316, so your results should apply to it. If a bottle were half-full on average, and opened for only 5 minutes when used, and kept refrigerated or frozen, I'd say it would last a few years.
Also, unlike XTOL which dies clear, the concentrate's colour tells us its state. Clear or yellow is okay. Orange means develop a little longer. Red probably means it's too far gone. Nice to know *before* developing film...