Hi widey,
[quote]I can imagine that there are only very limited scenarios where one will be able to try a topper before purchase. One scenario I can think of is when one is buying the mattress and the topper at the same time from the same store (and the store has the topper you desire in stock for you to try it).
My un-scientific guess is that most people don’t get toppers when they’re buying a mattress.[/quote]
There are a few manufacturers that have “sleeping systems” that provide the option of adding one or several toppers as part of the customizing options that are available when you are choosing a mattress. A few that come to mind off the top of my head are Pure Latex Bliss and Royal Bedding and Berkeley Ergonomics but there are certainly many others that carry a range of toppers that can be added to a mattress as a way to customize the mattress before a purchase. In most cases though … a topper would be a “backup strategy” that would be used by someone that chose a mattress that turned out to be too firm in spite of their “best efforts” to choose a mattress that was a good match for them in terms of PPP without an additional topper and where adding a topper was the best option available to them.
ADMIN NOTE:Removed 404 page link | Archived Footprint 1: royalbeddinginc.com/mattresses/mattresses-latex-mattresses/latex-3-toppers| Archived Footprint 2: berkeleyergo.com/engineered-designs/pillow-top.html
[quote]Which leaves me feeling there’s a high probability I’ll be making a mistake when buying a topper for my mattress? That’s unfortunate.
In my situation, I don’t want to get the latex topper that DixieFoam sells because it is too soft for my taste (and my lower-back). It’s a 3 inch Talalay Latex rated at 13 ILD. I need something firmer and thinner. I’m looking for something that’s rated at > 25 ILD and is 2 inch thick.
Let me know if you have any suggestions for a good medium-firm to firm Latex topper (Dunlop or Talalay) for my mattress spec? [/quote]
If you can’t test a mattress/topper combination in person then I would sleep on the mattress first for a while so you can use your actual sleeping experience on the mattress and how it feels to you as a reference point along with the information in post #2 here and the topper guidelines it links to as a guideline to help you choose the type, thickness, and firmness for a topper that would have the best chance of success. There are also several topper sources that have good exchange/return policies that can also help you lower the risk of making a topper choice that doesn’t turn out as well as you hoped for. The topper guidelines also includes a link to a list of the better online topper sources I’m aware of.
A memory foam layer under a relatively thin layer of latex or on top of the latex can both help lower the resilience or “springiness” of a latex top layer but memory foam on top will have a bigger effect than it will under a latex topper. This would be a preference choice and different people would have different preferences about using memory foam either under or over latex. My personal preference would be latex on top but this is because I prefer a more resilient sleeping surface that is less motion restricting and more resilient and others would prefer the same layers the other way around because they prefer the feel of memory foam more than latex. There is no “better or worse” in this … only preferences.
You certainly made a high quality/value mattress choice that would make a good “base mattress” for a topper … and congratulations on your new mattress 
Phoenix