Hi learningunderground.
Welcome to our Mattress Forum! 
and thanks for your kind words of appreciation.
I’m sorry to learn of your pre-existing preexisting medical conditions but as you surmised, it isn’t quite as cut-and-dry mainly because finding the best configuration for you will be specific not only to your symptoms but also to your particular alignment, comfort, and sensitivity thresholds. You are at a good starting point as typically people with similar conditions find it difficult to pinpoint if the pains that are mattress-related, medical, or both (and the percentage of each). There is some information about the many different symptoms that people may experience on a mattress and some of the most common causes behind them in post #2 here that you may find useful to peruse.
Both 8" and 10" Copenhagen are good quality mattresses with no weak links in terms of durability and you can see some basic benefits of euro (arched) slats systems They are typically used under thinner latex mattresses so that the mattress thickness does not negate the effect of the flexible slats. They can be part of the design of a sleeping system or can be used to fine-tune a mattress for better support/comfort match of each individual for reducing pressure points and increasing support in needed areas of the body and can also help with stabilizing the sleep posture if you sleep in one position only. A flexible support system under a mattress can change the feel and response of the mattress compared to a rigid non-flexing support system (which would be a more common choice for a latex mattress) This can be either detrimental or beneficial depending on which combination (your mattress on a flexible slat support system vs a rigid non-flexing support system) is the best match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences). When the euro slats are used they become an “active” part of a sleeping system just like any of the other layers or components in the mattress itself that compresses or flex under bodyweight so it can certainly affect the feel and performance of the mattress for better or for worse and while not impossible it can be problematic for combination sleepers to find the golden mean. As you can see on Berkley’s website, they offer flexible slats, flexible-adjustable slats, or plain solid wood foundations. In some cases, if each side of the support system has flex and there is no flex in the middle center support beam (or if you have two twin XL foundations side to side with the firmer edges in the middle) then you may be able to feel the firmer center support through the mattress. You can see some additional comments about flexible slat systems vs rigid non flexing foundations in post #2 here and post #2 here and post #13 here.
In the same vein…you may be interested to look at the CBH Wood’s “Tri-Slat” slat system consisting of latex on wooden slats in conjunction with the supportive latex strips, is placed on a solid wooden frame. This system allows for dynamic adjustments of the support/comfort functions of the bed due to the body’s weight, shape, and various sleeping positions, thus promoting adequate spinal and joint alignment. The system’s design has the capacity to accommodate a wider range of individual sleeping positions and needs. Here is what one of CBH wood customers with complex medical conditions reports about the Balancer system
As far as zoning goes … it can certainly be helpful in more unusual circumstances. With latex, zoning may not be as necessary because of the nature of latex itself and its higher compression modulus than other foams (particularly with Dunlop) but even here it can have some benefits and allow for the use of softer foam under wider/lighter shoulders than may otherwise be possible. There’s more about zoning and some of my thoughts about it in this article .
Zoning in a latex slab is achieved using different size pins to increase or decrease the amount of material in a section of the rubber which in effect alters the amount of material in that particular section which will change its overall density. Depending of the pin size used in a specific section of the slab results in a softer or firmer feel. Berkley uses “gentle zoning” with small differences in pin size between zoning sections. (e.g. the smallest pin size in their picture is around the edge of the slab which creates firmer perimeter support. The impact on durability is negligible. In addition to this, there is a 2" un-zoned softer comfort layer “buffer” and further away from direct mechanical stress. At your 21.5 BMI, I would not have any durability concerns or this zoned layer. One of the problems with zoning, however, is that people have different body configurations and heights and this zoning might not work for everyone as the zoning does not adjust to the size of the people.
I would certainly reach out to FloBeds ( our Trusted Members here ) as they offer a very competitive zoned system and I would use their advice picking out layers, as this has a little more science behind it and can get very complicated. You can reach them by phone or through FloBeds dedicated forum with the main area of expertise around latex and zoning and are very familiar with Berkley’s lineups and most likely the best to approximate the feel you like with the BE models.
I hope some of this information helps you out with your eventual decisions
Phoenix