Shoe life

They quit making my favorite shoe...Brooks Infiniti 2...a couple years ago. I'm running in Brooks Ravenna 3 but I prefer the Infiniti. I bought a couple pair when I realized they were going to quit making them. I still have one new pair in the closet. I was saving it for my next marathon attempt.
My question is...should I save them for my next marathon or go ahead use them now? Will the cushioning deteriorate sitting in the closet making them a poor choice for the marathon?

I asked a Brooks rep a similar question about the couple of pairs of the Launch that I bought, and he seemed to think that there would really be no issues. However, he also said to check them often to make sure the midsole felt the same.

Yeah, I seem to remember a study someone did on this very topic that basically said the same. As long as you keep them in relatively constant temperatures with no wild swings up to really high temps, they should be fine for a very long time. Maybe not 10 years, but 2-3 should be safe.

I got 4 pairs of original Nike Lunar Glides when they changed the design to something that I didn't like. Over two years later, I am starting in on my last pair and they seem absolutely fine. Fortunately I also found a new shoe that works for me during that time! Of course knowing my luck, they will probably redesign it.....

Thanks all...I'll save the shoes till a few weeks before the marathon and see how they feel.