Hi liaozhongchao,
I switched your post to a new topic with a new title since your question is outside of the scope of the original topic you posted in.
While other people’s comments or reviews about the knowledge, service, and guidance of a particular business can certainly be helpful … I would avoid using other people’s experiences or reviews on a mattress (either positive or negative) or “so called” mattress review sites in general as a reliable source of information or guidance about how you will feel on the same mattress or how suitable or how durable a mattress may be for you and in many if not most cases they can be more misleading than helpful because a mattress that would be a perfect choice for one person or even a larger group of people may be completely unsuitable for someone else to sleep on (see post #13 here).
You can also see some comments about these types of sites (such as Sleep Sherpa) in general in post #1 here in the simplified choice topic (and the video here it also links to). They are really nothing more than revenue sites that in most cases have little to no experience in the industry, have very little knowledge about mattress materials or mattresses in general, and are only in existence to earn the revenue that has become available as a result of the “new breed” of simplified choice online mattresses that are entering the market.
There isn’t much difference between going into a chain store and buying a mattress based on the “recommendation” of a salesperson that is just out of high school, knows very little meaningful information about mattress or mattress materials, and is just repeating the “sales and marketing information” they have learned (most of which is meaningless) for the sake of making their commissions and the many so called “professional review sites” that are little more than an online version of the same thing.
There are 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.
This is particularly true when you are comparing two mattresses that are in completely different categories and use completely different materials that “feel” and respond very differently from each other. The Nest Bedding Alexander is a memory foam mattress that has 3 different firmness options while the Tuft & Needle uses high performance polyfoam in their comfort layers and has a single firmness option.
While your own careful testing or personal experience is the most reliable way to know whether any mattress is a good “match” for you in terms of firmness, “feel” or PPP or how closely one mattress (or a specific firmness level in the case of Nest Bedding Alexander) “matches” or compares to another mattress … 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 firmness 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