Does anyone have an opinion on whether the extra money for the 13" makes a substantial comfort/durability difference? I’d appreciate any ideas.
A more detailed phone conversation or chat with Dreamfoam would be the most reliable source of information about the differences in how each of these mattresses may feel for you (which may be very different from how they feel for someone else) and they will have more knowledge and experience with matching their mattresses to different customers than anyone else.
In very general terms though the 13" gel memory foam mattresses would be similar to the Tempurpedic Cloud Luxe and the 12" Supreme gel memory foam mattress would be firmer and closer to the Tempurpedic Cloud Supreme. You could test both Tempurpedic mattresses locally to see which of them is the best match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) and use that as a reference point to help you decide between them.
There is more in post #13 here about the most important parts of the “value” of a mattress purchase but the suitability of a mattress for your body type and sleeping positions is always the most important part of “value”.
Thank you! I appreciate your taking the time.