Hi Thunderthud54,
I would probably consider the exchange so you can choose a mattress that would be more suitable for an adjustable bed.
The Palais Grand Royal uses the Tempurpedic Grandbed as a reference point in its default configuration but also has several options to customize it after a purchase (see post #6 here). If the Grandbed is your “target” then the Luxe Estate also uses the Grandbed as a reference point but doesn’t have the same custom configuration options as the Palais Grand Royal and it may also be too thick to use on an adustable bed. In this case it may be necessary to choose a mattress that “approximates” a different Tempurpedic mattress that is thinner for use on your adjustable bed.
In most cases a foam mattress (memory foam, latex, polyfoam) is a good choice for an adjustable bed … but 12" is usually a good guideline for the maximum thickness that would work well although this will also depend on the specific materials and construction of the mattress because different types or firmness levels of foam can also be more or less flexible so the suggestion of the manufacturer who will know more about which of their mattresses will work well than anyone else is usually the best guideline to follow. It would be a good idea to ask about this specifically in your conversations with them in case it doesn’t come up specifically.
I think your own experience in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) would be the only way to decide this. There is no “theory at a distance” that can provide a better answer than your own sleeping experience.
The only options I can think of if you don’t have an alternative use for it would be selling it on Craigslist or Kijiji (and you could also list it on the forum) in the hopes that someone may be interested in buying it. It may also be worth talking with Christeli about whether you could return it for some type of credit as an exception to their policy or as an alternative to a complete mattress exchange.
Phoenix