Hi jm1080,
There is no such thing as a “pure memory foam” mattress … at least that any reputable manufacturer would make.
I don’t consider any material or component “better” than another because the combinations of materials in a mattress are an individual preference and each person can be very different. It’s like asking if apples are better than oranges. It depends on the needs ad preferences of each person. The one common thing I would suggest is that no matter which type of material or components (like an innerspring) you prefer that you choose the highest quality and most durable version of that material or component that is possible. The “best” mattress for each person is what post #2 here is all about and it doesn’t say anything about which materials are used … only about the qualities and benefits the mattress that makes it suitable for a particular person and about choosing the best possible quality and value in your budget range so that the mattress will remain as close to its original feel and performance for longer than lower quality versions of the same materials.
Your jov is to find the materials and components that you prefer … and then find the design that uses those materials that best matches your needs and preferences.
I’m still not clear on which type of “hybrid” you are talking about because there are three different types of foam. You will find traditionial mattresses that use innersprings of many different types with polyfoam in many different combinations, innersprings that use different types of memory foam in different layers and in combination with other types of foam as well, and innersprings that use latex also by itself or in combination with other types of foam as well. All of these could be called “hybrid” mattresses because they use more than one material or component.
If you mean some type of innerspring/memory foam hybrid (probably with other materials in the mix as well) then if this is the best choice for you in terms of PPP (Pressure relief, Posture and alignment, and Personal preferences) then it can certainly make a suitable choice as long as the memory foam and any other materials are good quality.
There is no specific type of mattress that is inherently “good” or “bad” at back support or alignment. There are only mattresses that are good or bad in terms of back support and spinal alignment for YOU (whether they work well for anyone else is meaningless and irrelevant). Each of us are different.
Phoenix