Hi Lynni,
Post #1 here has all the basic information, steps, and guidelines I would use when shopping for a new mattress and as you mentioned I would avoid the major brands because they either don’t disclose the quality of the materials in their mattresses or in the much less common instances when they do they are consistently lower quality than smaller manufacturers across the country that sell mattresses in similar price ranges that use higher quality versions of the same materials. No matter how a mattress feels in a showroom … you can’t feel the quality of the materials in a mattress … and the useful life of a mattress is dependent on the quality of the materials in a mattress. Foam softening and breakdown that is much more likely with lower quality/density materials is not covered by any warranty even thouigh the loss of comfort and support that goes along with this is the most common reason that people nee to replace a mattress (you can read more about warranties in post #174 here).
Mattress reviews are also not the same thing as mattress research and are among the worst ways to choose a mattress. you can read more about this in post #13 here.
The Optimum line uses memory foam or gel memory foam in the range of 4 lbs which is a medium quality/density material but it’s not in the same “value range” as many other mattresses that use similar materials.
You can read more about the different types of mattress protectors and the pros and cons of each in post #89 here. There are no specific meaningful comparisons between the “semi-breathable” membrane types that I’m aware of that talk about the specific makeup of the materials or the relative breathability, waterproof performance, or stretchiness of each type of waterproof/breathable membrane but they tend to use either polyurethane, PTFE, polyethylene, or polyester and are either microporous or diffusion (monolithic) types. There are some general descriptions of the different types of membranes here and here and here for those who are more technically inclined but I would personally go with the suggestions of a more knowledgeable and experienced retailer or manufacturer that you trust because delving into the specs that are usually only of interest to or understandable by materials scientists won’t necessarily tell you much about how well a specific protector will perform in real life for you in terms of breathability, waterproofness, or stretchiness which are the most important parts of your choice. This is one of those cases where the knowledge and experience of who you buy from can be more important than the technical specs of the material or even the cost (within reason) because it’s unlikely that you will be able to find out the specs that compare them more directly in all the ways that may be important to you.
In the semi breathable / waterproof types … I would personally choose a natural fiber material (such as cotton) or a semi synthetic fiber (such as bamboo or some of the other rayon types of fabrics) than the synthetic type of fabrics like polyester regardless of the type of membrane.
Phoenix