Hi rdmathews.
Welcome to our Mattress Forum. 
I am glad to hear you’ve found resources here on The Mattress Underground that have been useful to you in your research and narrowing down your mattress options.
Thank you for sharing some of your sleeping stats with us. I am sorry to hear of your husband’s Ankylosing Spondylitis and understand that support and alignment here is of particular importance. With that in mind, with particular attention to the 3D Matrix by GhostBed, I would suggest taking a look at our Durability Guidelines as they pertain to memory foam and BMI, and reach out to GhostBed directly and share with them what you’ve shared with me. They know their product best and will be able to help you evaluate whether or not it’s a good match for you and your husband’s differing needs.
Latex is a wonderful, supportive comfort layer as well so it is great that you’re also considering latex hybrids. Latex has comparable pressure relieving qualities to memory foam due to its ability to form itself to the exact shape of your body profile while you are sleeping, and to do this instantly as you change positions. Latex and memory foam share this ability to form a pressure relieving cradle more than other more commonly used materials.
Because even in softer versions it has a higher resilience and is more “supportive” than other foams, it will also help support the more recessed areas of your body, such as the lumbar, that need “filling in” and are not in close contact with the firmer support layers underneath and because of its resilience it less motion restricting than memory foam and changing positions and other movement on the mattress easier.
Unfortunately I can’t tell you exactly how these mattresses are going to compare in terms of durability or feel as I have not slept on any of these mattresses for an extended period of time, and ultimately, my (or any other person’s) experience on these mattresses would be useless, as ultimately only you can feel what you feel on a mattress in terms of comfort as it relates to your specific needs, BMI, activities on the mattress, etc. What may feel firm for me may be supremely comfortable to you, etc.
Other Trusted Members that offer split latex configurations that you may be interested in browsing are…
Arizona Premium
Sleep EZ
FloBeds
Latex Mattress Factory
Nest Bedding
Regardless of which mattress you choose or may be considering, it’s important that you have a detailed conversation with the knowledgeable and experienced retailer or manufacturer who, and provide them with good information about your body types, sleeping styles, general preferences and history, some general information about mattresses you have tested and done well with, and any other specific information or circumstances that could affect your choice of a mattress.
I hope this helps.
NikkiTMU