Hi HeatherinMI,
You are certainly looking at a great quality/value choice but when you can’t test a mattress in person then the most reliable source of guidance is always a more detailed phone conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests at heart and who can help “talk you through” the specifics of their mattresses and the properties and “feel” of the materials they are using (fast or slow response, resilience, firmness etc) and the options they have available that may be the best “match” for you based on the information you provide them, any local testing you have done or mattresses you have slept on and liked or other mattresses you are considering that they are familiar with, and the “averages” of other customers that are similar to you. They will know more about “matching” their specific mattress designs and firmness levels to different body types, sleeping positions, and preferences (or to other mattresses that they are familiar with) than anyone else.
I would also keep in mind that there are also no “standard” definitions or consensus of opinions for firmness ratings and different manufacturers can rate their mattresses very differently than others so a mattress that one manufacturer rates as being a specific firmness could be rated very differently by another manufacturer. Different people can also have very different perceptions of firmness and softness compared to others as well and a mattress that feels firm for one person can feel like “medium” for someone else or even “soft” for someone else (or vice versa) depending on their body type, sleeping style, physiology, their frame of reference based on what they are used to, and their individual sensitivity and perceptions. There are also different types of firmness and softness that different people may be sensitive to that can affect how they “rate” a mattress as well (see post #15 here) so different people can also have very different opinions on how two mattresses compare in terms of firmness and some people may rate one mattress as being firmer than another and someone else may rate them the other way around. This is all relative and very subjective and is as much an art as a science.
Side sleepers in general tend to need a softer mattress than back or stomach sleepers and an online retailer will generally suggest a mattress that they believe will have the best chance for success (based on averages) since a return is very costly to an online retailer or manufacturer and it’s in their best interests to make a suggestion that they believe will have the least possible chance of being returned.
Since the only way to know for certain or confirm whether any mattress will be a good “match” for you in terms of comfort, firmness, and PPP or how it will compare to another mattress will be based on your own personal experience … if you aren’t confident that an online mattress will be a good match for you then the return/refund policy and any costs involved would become a much more important part of the “value” of a mattress purchase so you can try out the mattress in your bedroom instead of a showroom with the only risk being the cost of returning a mattress (which is the case of the BME is free) if in the worst case, and in spite of the “best efforts” of everyone involved (both you and the retailer you are buying from), the mattress doesn’t turn out to be as suitable a choice as you hoped for.
Phoenix