Hi comet,
Welcome to the Mattress Forum!
Much of what you’re asking comes down to personal preference, so there really wouldn’t be a right or wrong answer.
There’s more information about wool toppers and some of their advantages/characteristics in this post (and the posts it links to). Wool is a great material and many people have a preference for this as a topper as opposed to latex or other foams, and there’s certainly no harm in placing a wool topper over latex.
The primary “deep support” within a mattress comes mostly from the deeper firmer layers, and toppers (wool or otherwise) tend to mostly modify surface comfort. A wool topper can create a slightly softer surface comfort when placed over a firmer piece of latex, or slightly firm up the surface comfort when placed over a softer piece of latex. Wool will tend to compress a bit over time and can firm up slightly, and can be quite durable. Whether you would choose wool versus latex (Dunlop or Talalay) would again depend upon your goals and personal preferences. There’s more information of the differences between multiple styles of toppers in this post. There would be no empirical reason to replace your topper – only one of personal preference.
That’s one I really can’t explain. I certainly have my thoughts, which are shared by many people with whom I’ve spoken in the industry. From the retail standpoint, it takes a bit more education/knowledge and time to comprehensively explain the differences between blends of latex, certifications, Dunlop versus Talalay, ILDs, and so on, and as people on this forum are well aware, unfortunately a premium isn’t placed upon education and training in most retail establishments. Also, latex has a bit of a different feel, which not everyone may enjoy. The pricing for latex can be a bit higher, which can discourage some buyers. And for many salespeople, it is easier to sell what is advertised more on television and what has a bit of a “different feel”, such as the more “mainstream” products and memory foam. So, while this list isn’t complete, there really are many reasons.
Phoenix