Hi griffin.
Welcome to our Mattress Forum! 
It is always very rewarding and makes things so much simpler when consumers take a bit of time to understand their sleeping landscape. You are correct and seem to be heading in the right direction. It sounds like you did some good research and have a very good understanding of what your needs are … and you are also wise to make some provisions for fine-tuning of the sleeping system if need be by choosing a mattress that can be customized after purchase.
I heartily agree with you…the two main functions of every mattress are to keep your spine and joints inside the range of their neutral alignment in all your sleeping positions and to relieve pressure by redistributing your weight across the surface of the mattress. Sometimes it can be a struggle to tune in on the correct combination of primary/secondary support and comfort for your particular needs and preferences especially when dealing with higher weight differential between sleeping partners as you both will need different contour and support configurations at your respective weights and sleeping positions. I’ll only add a couple more thoughts that may be helpful in your final selection that you may wish to look into:
Your husband’s BMI is 33.67 kg/m2 which is higher than yours at 25.02 kg/m2 so you may also wish to consider a split side by side option to ensure the softness/firmness suitability for both. With your prone sleeping position, you’d also need a firmer sleeping surface too and you may wish to review the guidelines in this [url=Your sleeping style, preferences, and statistics - Your sleep positions - The Mattress Underground] Sleep Positions Article [url] so that you avoid hyperextension in a swayback position that can cause back issues. You did not mention what your husband’s sleeping position is but from your description it sounds like he sleeps on his side and he’d certainly need a bit more pressure relief and a softer/thicker comfort layer.
Just in case you missed it Post #3 here(which I think you may have already found) has more information and suggestions about heavier weights that is worth reading. A high BMI presents special challenges and generally requires firmer materials (which is good because it can go hand in hand with your prone sleeping position) Heavier people, in general, will need firmer and thicker comfort layers and firmer support layers than those who are lighter and because no materials will last as long with much higher weights the quality and durability of the materials and components is even more important than normal.
Your choice of materials within the mattress you “narrowed down” is very appropriate for the issues you mentioned… Latex, in general, is also the most breathable and “temperature neutral” of all the different types of foam materials so this along with the Joma Wool used within the cover, and natural cotton. will certainly help with the night sweats.
Latex allows for more air flow than any other foams and when changing positions on the mattress the air will be moved in and out like within an accordion. The issue of the sleeping microclimate on a mattress is a complex one and each layer of a mattress … especially the ones that are closest to the body … contributes to the overall effect in one way or another and of course, there are many other factors involved such as how deeply you sink into insulating materials that have different ventilation levels (this is connected to the comfort of the mattress). Hopefully, this will fill in any gaps that aren’t in the other posts I linked.
There is more about the many variables that can affect the sleeping temperature of a mattress or sleeping system in post #2 here that can help you choose the types of materials and components that are most likely to keep you in a comfortable temperature range. Latex itself is a quite breathable material.
In a way I am glad that you have one more reason to stay away from B&B and “Hotel mattresses” because they tend to be lower quality and value than the consumer mattresses made by the same manufacturer in the same price range and more basic versions of the retails products that many mattress companies offer (which isn’t a good thing). It usually depends for how long they’ve been uses and broken they are in their life cycle but one of the “secrets” to many hotel and B&b mattress is that they usually use a bedding package that includes a mattress pad or topper that is a big part of how the mattress feels and can also add to the durability of the mattress (replacing a mattress pad or topper can be less costly than replacing a whole mattress because a mattress or sleeping system will usually soften or break down from the top down). In many cases, the more subjective short term experience of sleeping at a hotel is an improvement over the mattress that people sleep on regularly and this often “translates” into the perception that hotel mattresses are better than they are. They are a frequent source of buyer’s remorse. They tend to be firmer products using softer “top-of-bed” materials to create extra plushness. There’s more good information about hotel mattresses in post #3 here.
Nest Bedding as you probably know are a member of this site which means that I think very highly of them and that I believe they compete well with the best in the industry. They offer excellent customer service and have staff that will guide you through your choices to ensure suitability and I’d make sure to reach out to them for guidance.
Note: Once you’ve had the chance to see my reply here I’ll be moving your post to a different thread to better reflect the topic.
Let us know what you’ve decided and of course, any other questions you may have.
Phoenix