Hi Wlee,
Both the Savvy Rest and the Sleeping Organic use good quality materials. Savvy Rest offers natural Talalay from Radium and GOLS certified Dunlop from Coco Latex. Sleeping Organic offers natural Talalay, natural Dunlop and GOLS certified natural Dunlop. Savvy Rest offers three different comfort designations in their foams (soft, medium and firm) while Sleeping Organic offers four different comfort designations of their foam layers. Both use similar covers. Savvy Rest does allow for a one-layer exchange for a shipping fee within 90 days, and as you mentioned Sleeping Organic does have the 45 night return policy and a layer exchange program within 100 days. While Savvy Rest does use good quality materials, I would make some careful personal value comparisons, as they are in a bit of a higher price range. As I think you may already be aware, Sleeping Organic is a member of this site which means that I think very highly of them and that I believe that they compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency.
You can read more about ZenHaven in the simplified choice thread here. It uses good quality materials and is all-Talalay, and is a flippable product with different comforts on each side that is not configurable, so it would be “less like” the other two mattresses you mentioned.
The “value” of a mattress purchase is what is most important and price is just one of many factors that can affect the “value” of a mattress purchase. 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”. The value of a mattress purchase is also relative to how a mattress compares to the other finalists you are considering. There is more about the 3 most important parts of the “value” of a mattress purchase in post #13 here which can help you make more meaningful quality/value comparisons.
Phoenix