Hi curimattrous,
There is more information in post #9 here about the different ways that one mattress can “match” or “approximate” another one. Every layer and component in a mattress (including the cover and any quilting materials) will affect the feel and performance of every other layer and component and the mattress “as a whole” so unless you are able to find another mattress that uses exactly the same type of materials, components, cover and quilting, layer thicknesses, layer firmnesses, and overall design (which would be very unlikely) then there really isn’t a reliable way to match one mattress to another one in terms of “comfort”, firmness, and PPP based on the specifications of the mattresses (even assuming that you can find out all the specifications you would need for both mattresses you are comparing in the first place).
Mattress manufacturers generally try to differentiate their mattress from the mattresses made by other manufacturers and don’t normally try to “match” another mattress that is made by a different manufacturer so unless a manufacturer specifically says in their description of a mattress that one of their mattresses in the same general category is specifically designed to “match” or “approximate” another one in terms of firmness or “feel” and PPP and/or they are very familiar with both mattresses and can provide reliable guidance about how they compare based on the “averages” of a larger group of people that have compared them (different people may have very different opinions about how two mattresses compare) … the only reliable way to know for certain how two mattresses would compare for you in terms of how they “feel” or in terms of firmness or PPP (regardless of anyone else’s opinions of how they compare which may be different from your own) would be based on your own careful testing or actual sleeping experience on both of them.
Having said that … if you are researching online memory foam mattresses then the mattress shopping tutorial includes a link to a list of some of the better online memory foam options I’m aware of (in the optional online step) and several of them make memory foam mattresses that they describe as being reasonable approximations of many of the Tempurpedic mattresses. Several of the other retailers or manufacturers that are on the list that don’t specifically describe their mattresses as being similar to one of the Tempurpedic models would probably also be able to give you more information about which of their mattresses would be the closest approximation to a Tempurpedic mattress that you prefer as well.
I would also keep in mind that different people can have very different opinions about how a mattress feels or compares to another mattress. The “feel” of a mattress is also very subjective and isn’t the same thing as the firmness of a mattress or whether a mattress is a good “match” for you in terms of “comfort”, firmness and PPP so another memory foam mattress may have a very different “feel” but still be just as suitable for you to sleep on, just as durable, and have a similar firmness level.
The only manufacturer on the list that I’m aware of off the top of my head that sells a mattress that they compare to the Tempurpedic GrandBed is Christeli and they compare both their Palais Grand Royal and their Lux Estate mattresses to the GrandBed. Their designs are different however because both mattresses include latex support cores (which is a different but higher quality material than the polyfoam that Tempurpedic uses in their base layers) and their memory foam thicknesses and densities and “feel” are also different from the memory foam layers in the Grandbed but there are no lower quality or weak links in either mattress. I would also be aware that they only offer a 50 day exchange policy and don’t have a return policy so if you purchase a mattress from them that isn’t as suitable as you hoped for then you will only be able to make a single exchange for a different mattress … although they do provide good guidance to help you decide which of their mattresses would have the best chance of success.
I would also make sure that you have done some careful testing to confirm that the Tempurpedic GrandBed really is the best “match” for you in terms of comfort, firmness, and PPP out of all the mattresses they offer and that you aren’t just assuming that it’s somehow better for you because it’s their most expensive mattress because any mattress (including the GrandBed) may be a good choice for some people and may be completely unsuitable for other people to sleep on regardless of the price.
Phoenix