Hi santamonicagal.
I am sorry that your choice did not work as well as you have hoped for, but the good news is that you do have some good options to find find the right comfort/support combination for you and your husband.
I would agree with you that although commonly used to fix a mattress it is good to avoid adding to your firmer mattress a separate topper afterwards unless there is no other reasonable alternative or unless you have a chance to do some careful and objective testing for PPP (Posture and alignment, Pressure relief, and Personal preferences) on the specific combination in person using the testing guidelines in the mattress shopping tutorial . Deciding on a topper that would be a good match for both you and the mattress (the specifics of the mattress can make a significant difference in which topper would work best for you) can be almost as challenging as buying a new mattress in the first place.
It’s also important to know that any topper (or top layer) will interact with all the other layers in the mattress you have and the same topper can feel quite different on different mattresses. Your own body type, sleeping style, preferences, and sensitivities to different foam properties will also change what one person feels on a material compared to someone else. I would recommend that before you decide to go one way or another you revisit Nest showroom and test the medium version of the Next Latex hybrid and discuss your options. They are extremely Knowlegeable and offer great customer support and after purchase options.
Having said all that … if your mattress is still too firm and going with the medium version of Nest hybrid would not meet your support requirements for proper alignment and you only need some extra pressure relief then a topper can be a good choice to improve your existing system and the topper guidelines in post #8 here and the posts it links to. A good quality topper can certainly be an effective way to add some additional softness, “comfort” and pressure relief to your sleeping system but the only way to know for certain whether a specific mattress/topper combination is a good “match” for both of you in terms of comfort, firmness, and PPP is based on your own careful testing or personal experience on the combination. If you can’t test the combination in person then there will always be always some risk and uncertainty involved in adding a topper because the specifics of the mattress itself along with your own body type, sleeping position, and preferences can affect which specific topper would be a suitable choice on any specific mattress.
There is more information about choosing a topper and a link to the better online sources I’m aware of in post #2 here which along with a conversation with a reliable and knowledgeable supplier (that can provide you with good information about how their toppers compare to each other or to other toppers they are familiar with that are available on the market) can help you use your sleeping experience as a reference point and guideline to help you choose the type, thickness, and firmness for a topper that has the least possible risk and the best chance for success. A good exchange/return policy can also reduce the risk of an online topper purchase so I would make sure you are comfortable with the options you have available after a purchase just in case the topper you choose doesn’t turn out as well as you hoped for.
Nest also has a good 1.8 lb Polyurethane topper that is designed to work in combination with their systems in case extra plushness is needed. (it is not latex as you would like but it is a good quality topper that is worth checking) I suggest that you call Nest and have detailed conversation with them about your options. (before engaging in purchasing a topper as a way to fix your mattress)
This assumption is incorrect as there as toppers can be latex as well as other types of materryals (poly, micorcoil, memory foam, wool….) As you like the feeling of latex then I would trust the feeling that your are familiar with and look for a latex topper option.
Keeping in mind that most of the toppers being offered are coming in 2"- 4" thickness, here are some of [url= https://mattressunderground.com/the-underground/our-trusted-members.html]our trusted members[/url] who offer latex toppers that could fit your criteria.
Sleep EZ has 2" or 3" NR Talalay & Dunlop toppers
Arizona Premium 2" or 3" Talalay & Dunlop toppers
Foam Sweet Foam Has 3" toppers both Talalay and Dunlop
Latex Mattress Factory 2" or 3" toppers
My Green Mattress Dunlop topper
Sedona Sleep a 3" Talalay blended Latex topper with zippered bamboo cover http://sedonasleep.com/talalay-latex-mattress-topper/
I hope this gives you enough information to help you weigh your options and perhaps return here to let us know.
Phoenix