Hi Owos,
You’ve certainly narrowed down your choices to some good quality/value options but like you I would want to know the type and blend of the latex and the density of the polyfoam in the Modern Sleep 11" Pristine. I believe that this is the same mattress as the Classic Brands Eden Latex mattress. It is most likely blended Dunlop latex which is a lower cost version of latex but they don’t say the blend of synthetic and natural rubber in the latex which I would want to know. This doesn’t mean it’s a poor quality material (any latex is a better quality choice than most polyfoam) … only that it’s a less costly material than 100% natural Dunlop latex and may be less durable and have less elasticity and resilience as well. I would also want to make sure that it hasn’t been compressed over a long period of time in storage because the durability of any foam, including Dunlop latex, can be reduced with long term compression (see post #6 here).
It also doesn’t say anything about the firmness/softness of the latex and if it was me I would want to talk with someone that had enough knowledge and experience to provide some guidance about whether the mattress would have reasonable odds of being suitable for my body type and sleeping style. A big part of the value of every mattress purchase is your confidence that the mattress is suitable for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) and the options you have to choose the comfort level of your mattress along with the options you have to change it (or exchange or return it) after a purchase can also be an important part of each person’s personal value equation. No matter what the quality or value of a mattress if it isn’t suitable for your needs and preferences it would have little value to you.
As you know I also think highly of Jim at Oklahoma mattress and the custom mattresses he makes. He does make latex mattresses as well as latex hybrids but I don’t know the specifics of their models and I would call and talk with them to find out more details. They are well worth a visit for anyone in reasonable driving distance and they have the advantage of being able to test a mattress for PPP (Posture and alignment, Pressure relief, and Personal preferences) before a purchase.
Other than the comments about Classic Brands … all your choices are between “good and good” and are made by a member of this site which I think highly of and have good quality/value throughout their lineup. They both have the knowledge and experience to give you some good guidance either on the phone or in person. Once you have narrowed down your options a little more I would make your final choice based on which one is the closest “fit” to all the parts of a mattress purchase that are most important to you (including your confidence in the suitability of the mattress and the importance of your options after a purchase if you make a comfort choice that is less than ideal).
Phoenix