I'm here now, and I'm happy to say that the sofa beds are new and very much improved. They are quite comfy. I'm not sleeping on one, but my DD8 is sharing one with DM76 and they are both sleeping very soundly.
Additionally, my DSis and her family are also sharing a studio, and they say the sofa bed is just fine.
As the person who folds it up and sets it up again every day, I can also add that it is very easy and convenient.
Can't comment on the bed mattress because I had no complaints to begin with so I don't notice a difference.