Hi Quickstrike,
I can certainly understand the hesitancy and there are many others that share your feelings about purchasing online as well.
The biggest disadvantage of course is that you aren’t able to test the mattress in person before you purchase it. Online “simplified choice” mattresses with multiple firmness choices such as the BME will cover a larger part of the bell curve that will be suitable for more people than single firmness choices but you will generally find that any one of these mattresses will be the “best” match (in their budget range) for a relatively small percentage of the population, a “good” match for a larger percentage, and an “OK” match for a larger percentage yet. While the only reliable way to know which group you fit in will be based on your actual sleeping experience when you receive the mattress … for those where the mattress isn’t a “good enough” match (either too firm, too soft, or where you experience “symptoms” when you sleep on the mattress) then they all have a trial period with a great return policy that lets you test the mattress in your bedroom instead of a showroom and then if your experience indicates that it wasn’t a suitable choice you can start all over again with choosing another mattress with little risk outside of the time you spent trying the mattress or returning/donating it.
While your own careful testing or personal experience is the most reliable way to know whether a mattress is a good “match” for you in terms of comfort and PPP … 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.
Phoenix