Hi carmutt,
Are you sure this is the Orthopedic Pillowtop (which lists for $849 queen set) and not the Orthopedic Eurotop (which lists for $1149 queen set)?
Density and softness are very different and only have a very loose connection with polyfoam materials. Any density of foam can be made in a wide range of softness levels. Higher density polyfoam will be more durable so it will tend to maintain its softness level and height much longer than lower density polyfoam of the sasme softness/firmness level. In general, once there are about 2" or more of lower density polyfoam in the upper layers of a mattress (1.5 lbs or less) I would be a little cautious because foam softening will have a greater effect on the feel and performance of the mattress and if a mattress is already on the soft side then the initial foam softening of all foam materials or the more rapid foam softening of lower density materials could easily put you “over the edge” of your pressure relief and alignment “needs”. This would be more true in a one sided mattress than with a two sided mattress. You can see a little more about how this can happen in post #2 here and you can read a little more about the factors that can affect the relative durability or longevity of a mattress in post #4 here.
If a foam is deeper in a mattress then the layers above it will absorb some of the compression forces in a mattress so a 1.5 lb polyfoam layer that has 4" of foam above it will be more durable than the same layer used closer to the top or on top of a mattress with less or no foam above it. Firmer foams won’t compress as much as softer foams so they will tend to be more durable as well. The 3.0 lb polyfoam is a very high quality material and has good durability (although all foam will soften over time just at different rates). A two sided mattress will also give the foam layers time to rest and recover and they will soften more evenly. Normally I would consider around an inch or so of lower density or quality materials in the upper layers to be acceptable in a one sided mattress and be cautious once the total thickness reaches 2" or more. In this case there is 2" but one inch of this has 4" of foam above it and it is two sided so it would be more durable than if the mattress one one sided.
With a mattress like this … I would be more concerned with it’s suitability for your needs and preferences. Even though it is probably fine in terms of the durability of the comfort layers (both because of the design and because it is two sided) … there is enough softer material in the top layers that I would have some concern that even a slower rate of foam softening (both initially and over time) could result in the loss of comfort and support because it may already be at the softer end of what would work well for you in your actual experience when you sleep on it. Don’t forget that comfort is generally what you feel when you first lie on a mattress but alignment and support is what you will feel when you wake up in the morning and needs more careful testing. There is also a lot of soft foam on the bottom of the mattress which could also affect alignment in a two sided mattress and I would be cautious and test carefully with comfort layers that are more than about 3" thick in a two sided mattress.
It would also be reasonable to expect that there would be some degree of impressions in the mattress over time although to a lesser degree than pillowtop mattresses that used lower quality materials (which includes most of them) and probably not to the degree that it would have an impression deep enough to be considered a defect and become a warranty issue. The biggest concern with a mattress like this would be foam softening and the likelihood that the loss of comfort and support along with having thicker layers of soft material on the bottom of the mattress could would take you over the edge and be somewhat risky in terms of alignment. I would even have the same caution about the risk of alignment issues with a mattress that used thick layers of soft latex in the comfort layers (which is an even higher quality material). Your careful and objective testing though is the best way to test for alignment and I would go no softer than you need to in any mattress choice regardless of material because it’s much easier to add softness to a mattress than it is to make a mattress that is too soft any firmer because this would generally require an exchange or the removal and replacement of layers 9adding a firm topper over layers that are too soft or thick is not effective).
As you can see these types of assessments are partly a science and partly an intuitive art but they can provide a guideline of what to look for and where caution may be necessary.
The Orthopedic Premier Pillowtop is 15" thick (and the Orthopedic Pillowtop is 12.5") so there would be more foam on either side of this one than just 2" of 1.5 lb density polyfoam. Are you sure that the specs you have are referring to the right mattress? In a two sided mattress that uses around 3" or less of 1.5 lb polyfoam it can be a durable material (if you regularly turn and flip the mattress to give each side a chance to rest and recover and soften more evenly) but if there is more than this I would be very cautious in terms of alignment and in terms of durability … even in a two sided mattress. “Just enough” softness to relieve pressure in all your sleeping positions is usually the least risky in terms of alignment.
You can read a little more about the benefits of the various types of gel and gel foam materials (including gel memory foam) in post #2 here. The cooling benefits of gel tend to be temporary and can help when you are going to sleep but not so much over the course of the night. A bigger benefit of gel when it is added to memory foam is that it can improve the support qualities of the memory foam and decrease its tendency to get softer over the course of the night (called “foam creep”).
I would keep in mind that there are no “recommendations” for a mattress design anywhere on the site or even basic generic guidelines that can possibly be more accurate than your own experience. There are some guidelines and information that can give you some insights into some of the “art and science” behind mattress design theory that can be a useful starting point but ILD or “comfort” information is not really relevant when you are testing a mattress locally. Mattress design and theory is very complex and all the layers and components interact with and affect every other layer to different degrees and each person can be very different in terms of their needs and preferences.
I would completely avoid any reliance on “comfort specs” or design when you are testing a mattress locally (because 99% of consumers would not have the knowledge to take all the related information they would need to make the comfort specs relevant) and focus on accurate and objective personal testing along with identifying any potential “weak links” in a mattress and knowing the quality specs that can affect durability and the things you can’t test for. When you focus on comfort specs with local testing you are generally heading into a “no mans land” of an art and a science that may take years to understand well enough to make any kind of mattress choice based on them and for most people too much information of the wrong type will lead to just as many poor choices as too little information and can lead to “paralysis by analysis”. Connecting with experts that already know what you would otherwise need to learn and using their knowledge and experience is much more effective than trying to “design” an ideal mattress based on specs that may take years to become meaningful to you. For comfort and support I would use careful and objective testing and then use specs to be able to identify potential risks that you can test for, potential weak links in a mattress in terms of durability, and to make meaningful comparisons in terms of quality and value (not comfort or support). Chuck at Rest Assured (and his staff) would certainly be in the “expert” category and I think very highly of them.
While there are many good online options that have less risk because of the ease of returning layers or the mattress itself … there are many people who like you are also very hesitant about the greater risk of buying something as important as a mattress online and will only buy locally. Local purchases are probably about 80% or perhaps more of all mattress purchases. In this case the best “local value” becomes important but each person may have different criteria for their personal value equation and make different choices once they have eliminated all the worst options and are at the point of making final choices between “good and good”. “Value” is always the combination of all the objective, subjective, and intangible factors involved with every mattress purchase that are most important to each person.
Phoenix