Hi kgoody,
If these are mattresses that were before the Spring Air acquisition then they would be prior to April, 2012 and it’s possible that these are returns of some kind (possibly defective) since it would be unlikely that they are new after that long. The manufacturing date should be on the law tag. Either way … if they are returns or pre-bankruptcy … then they wouldn’t have a warranty. The Natura IM perfec was apparently 3" of latex over a polyfoam support core (see here) and was introduced somewhere around early 2009 but I don’t know any details about the others. I did check the Naturaworld site on the wayback machine to see if they were listed but I didn’t find any listings for either the Heather or Cadence going back to about 20009.
Glideway/Sleep Harmony doesn’t use 1.5 lb memory foam in their mattresses (which would be a polyfoam density not a density for memory foam) and most of their mattresses use higher density memory foam … often in the 5 lb range … which would be the most likely reason it has lasted for so long.
If you like this mattress then it seems that you may prefer memory foam mattresses. There is more about the different ways that one mattress may “match” another one in post #9 here but without any information about what is in your mattress the only way to try and “match” it to another memory foam mattress would be based on your own testing and how it feels to you.
Glideaway still makes some good quality memory foam mattresses so it’s possible that one of their current models would be similar but again you would need to test it in person to assess whether any of them feel similar to the one you are sleeping on.
Just in case you haven’t seen it yet … the better options and possibilities I’m aware of in the Sacramento area (subject to the guidelines here and the steps in the tutorial post) are listed in post #5 here.
Phoenix