Hi Redbaron.
Welcome to our Mattress Forum. 
Glad to hear the information on the site has been useful thus far in your mattress search!
Thanks for sharing your stats with us! As you’ve probably already read in our article on [URL= https://mattressunderground.com/mattresses/style-preferences-and-statistics/your-sleeping-positions]sleeping positions[/URL], side sleepers have deeper gaps to “fill in” and tend to “sink in” deeper within the mattress due to a smaller surface contact area. which is why it is important that they have thicker comfort layers. Most side sleepers will fall in the range of needing a 2" - 4" comfort layer. Without an appropriate comfort layer, a side sleeper can experience pressure points during the course of the night that can result in numbness, soreness, localized redness, or end up tossing and turning all night as the body tries to adjust to relieve the pressure.
Looking at the specifications of the mattresses you’re considering, both appear to fall into that 2" to 4" range. Booth these mattresses are fairly thick (12.5"and 14.5"). Unless you prefer a thicker mattress I would say that at your BMI a 10" would be more than enough to accommodate your side sleeping.
Some of the price difference between the two can be accounted for by the extra latex layers in the Todalgo. Unless you really have a good reason to want a thicker mattress I would opt for the Trinidad As far as the density of the support core goes, the general recommendation for polyfoam is at least 1.8 lb per cubic foot or higher for a one-sided mattress for normal BMI weight ranges. I would try to find out the density of the 2" supper soft foam as this may start to break down and develop impressions in the future, especially as you are sensitive and already have pains due to your current sagging mattress. You are correct that the general recommendation is to use around an inch or so of lower density foams in the comfort layer. Other than this slight caution, all other materials used in this mattress meet the mattress durability guidelines.
Value is one of those things that is hard to qualify. Retailers and manufacturers have different reasons for pricing beyond just the materials. There isn’t a “formula” that can be used to assess or “calculate” the value of a mattress because there are so many different variables and criteria involved that can affect the price of a mattress that can each be more or less important to some people and not to others who may have completely different criteria or definitions of “value” and only you can decide this based on your personal value equation and all parts that are most important to you (including the price, of course, adjustability, and the options you have available after purchase if your choice doesn’t turn out as well as you hoped for). I’d base this value comparison on your testing, experience, and options they have …. Is this worth the price to you?
This being said, you can make some “value” assessments based on materials alone. Have a peek at one of our Trusted Members that provide similar materials. I used Arizona Premium as an example as they sell separate DIY components (which include polyfoam) You can see some price points for your comparison: 7" layer of polyfoam at $249 + 2" medium Talalay at $199 (sale price), and let’s say the same for the 1" Gel latex on top and the 3/8 layer would be around the same. Then let’s add a base at $249 and a zippered cover to enclose all layers for about $200… You would pay around $1,100 for a system that you can fine-tune for firmness/comfort down the road if something is not quite right.
Super soft foam of any kind breaks down faster than a firm foam of the same ILD/IFD. As this is something you’re already experiencing on your current mattress, I am glad you are now assessing any potential points of failure. That said, I wouldn’t be too alarmed by the extra inch of polyfoam, since there are substantially more durable and firmer latex layering under it. I would definitely pay some attention to the way it is built, tufting, etc.
As I mentioned above it ultimately comes down to your personal preferences and whether you feel you need the extra thickness and feel that Tobago is your best fit and worth the extra money. If you haven’t done so already, you may want to review our article on [URL= https://mattressunderground.com/mattresses/style-preferences-and-statistics/your-preferences]personal preferences[/URL] and all the other parts of your personal value equation that are most important to you (including the price, of course, and the options you have available after purchase if your choice doesn’t turn out as well as you hoped for) before making your ultimate decision.
As one caveat, I would avoid pillowtops and all “thick top” mattresses no matter what names they are given unless you know for sure that they contain high-quality materials that will not be the source of problems in a very short time.
Thanks for considering our Trusted Members ! The best way to shop for a mattress through one of our trusted members without being able to test prior to purchasing is to have a chat with them (either through actual live chat on their sites, if they offer it, or on the phone) and share your preferences and sleep statistics with them. Our trusted members have been carefully vetted and, if they don’t feel they have a mattress that fits your needs, they will point you in a different direction.
Based on the fact that you appear to be considering all-foam builds, I would recommend you look at the following:
Arizona Premium
Sleep EZ
Cozy Pure
FloBeds
Latex Mattress Factory
My Green Mattress
Mattress to Go
It’s possible I left some great options off the list, so definitely look through our Trusted Member directory in your own time, and don’t forget that a lot of them also offer discounts to TMU subscribers like yourself!
I realize I’ve also given you quite a lot of information, so if you have additional questions, please don’t hesitate to ask.
Phoenix