Difference Between Serta iSeries 1000 and 3000 worth it?

I’m stuck between these two models. They are both medium firmness but the 3000 had an extra layer of special cooling foam that the 1000 doesn’t. This also makes for a slightly softer feel which I like (but my husband is more firm, gets hot easily, but is in camp “just get whatever you feel is best” at this point). We are getting an adjustable base through Sam’s club (thanks for the suggestion to you all!)

What I’m wondering is, is the cooling really that much better? And does having that extra layer of cooling foam contribute to a longer-lasting quality? Trying to decide if it’s worth it especially since the fact that a hybrid means it will already be a bit cooler and the adjustable base will help with comfort.

Thanks!