Hi goitsme48,
Post #2 here will help you compare the pros and cons of option #1 and option #3 (and any of the ones on their site with a replaceable latex layer).
The choice of option 2 would be the choice for people who know they prefer a memory foam comfort layer over a latex comfort layer. They have said it has a similar but just slightly firmer “feel” than the Tempurpedic Cloud Luxe (which you could test locally).
The thickness of a mattress has little to do with how well it may help anyone’s back. It’s always the materials in the thickness and the mattress design’s ability to keep your back and spine in neutral alignment in all your sleeping positions. For some a thinner mattress may work better while for others a thicker mattress may work better in terms of providing optimal spinal alignment. The first link also includes a link to another post about the potential benefits for some people of a thicker mattress.
Post #326 here may also be worth reading about mattresses and various “symptoms” including back pain.
Phoenix