Hi BVavra,
I’m sorry to hear that you are having such trouble finding a mattress that you sleep well on but it’s good to hear that TMM had been so generous with their return policy. It’s very unusual that any manufacturer would take back 3 different mattresses.
Unfortunately the odds are low (see this article) that either the store or Aireloom will provide you with all the information you would need about the materials and components inside their mattress to make an informed choice and confirm that there are no lower quality materials or weak links in their mattress that would be a reason for concern in terms of the durability and useful life of the mattress.
As you can see in the guidelines here … I would avoid any mattress where you aren’t able to find out the type and quality/durability of the materials inside it (see this article) and confirm that they meet the minimum quality/durability guidelines here. This doesn’t mean that the materials would be either good or bad … only that there would be no way to know which would make it a very high risk purchase unless the durability and useful life of the mattress isn’t particularly important.
Phoenix