Soooo.... It's Day 5 with the new mattress and, while it's not everything I hoped for, I'm happy and optimistic for the future. (*I'm used to an adjustable air-filled mattress, so having a non-adjustable mattress takes a little getting used to.)
The first noticeable thing was NO OFF-GASSING ODOR!!! I could bury my face into this mattress right out of the box. Kudos to Avocado for that.
The second noticeable thing is this mattress isn't structured for prolonged sitting in bed (something I had hoped for). On a positive note, the mattress is 7/10 firm, just like Avocado said it would be, and a folded cotton blanket under my butt is all that is needed to be able to sit in bed 3-5 hours without my neck going out of whack.
At 11" in height, it is higher than my old mattress. That's without a pillowtop, since I didn't want a softer mattress.
And it is certainly comfortable. I've been less achy when I woke up the past few days. I'll report back in a month...