Hi jcurti02,
The closest of the forum lists to you that includes some of the better options and possibilities I’m aware of would be the Albany list in post #4 here and the Springfield / Northampton, MA list in post #4 here.
Rocky Mountain Mattress is a member of this site which means that they fully disclose the quality of all the materials in their mattresses and compete with the best in the industry in terms of quality, value, and service. Knowing the suitability of a mattress though for your specific body type or sleeping positions and preferences or knowing how one mattress compares with another in terms of feel and performance would be up to your careful and objective testing for PPP (Posture and alignment, Pressure relief, or Personal preferences) or if that’s not possible because they are sold online then a more detailed conversation with the manufacturer or retailer is the best way to make more meaningful comparisons. Post #2 here has more about making mattress choices in terms of PPP but with online purchases the retailer or manufacturer will know more about their mattresses and how they compare and provide better guidance than anyone else. In some cases they may also be able to tell you which mainstream mattresses their online mattresses approximate so you can test something similar locally to use as a guideline.
No … they use a different type of latex and have a different design than any of Rocky Mountain’s mattresses so they are both different although Spindle is also a member here and also competes well with the best in the industry.
Just in case you haven’t read it yet … the basic tutorial post here has all the basic information, steps, and guidelines that can help you make the best possible choices for your specific needs, preferences, and budget.
Phoenix