Interesting. I knew guy I traveled with who had back issues and specifically loved the Fairfield mattresses. And we traveled a lot, always stayed at Marriott properties and he insisted that the Fairfield mattress was the one he liked the best. This was about 4 years ago. I don't know if they've changed, and also, I don't know if they're really all the same. Come to think of it, though, I like Marriott and Renaissance beds better than JW, so, I guess they are different.

Serta claims that they have, or can get, a mattress from specific hotel brands. https://www.serta.com/mattresses/hotel-collections

But who knows. The mattress industry is pretty difficult to navigate.

Maybe someone at Marriott Insiders knows, or will tell. Or, have you asked the GM at one of the Fairfields you've stayed at?