Hi JimA,
I would add a “ditto” to diynaturalbedding’s comments here …
Wool is a great material that is a strong preference for some people and there are certainly some good benefits to sleeping on wool but I will echo diynaturalbedding’s comments that it will be different and firmer than sleeping on a soft foam material (and it will also get a little firmer as it compresses over time).
The type of breed used for the raw wool and the thickness and resilience of the wool fibers, the compression of the wool batts, the tufting or quilting of the topper, and the overall construction and layering of the topper along with the amount of wool inside will all affect the feel and performance of the wool topper so I would suggest a conversation with any retailer or manufacturer you are considering to talk about a specific topper and your experience on your mattress if you aren’t familiar with a specific wool topper or with wool toppers as a whole.
A queen size topper is about 3.7 yards.
The Flobeds wool topper would be 6.75 lbs / 3.7 = 1.82 lbs/yd of wool
The Solus wool topper is listed as about 2 lbs/yd which would be 3.7 x 2 = 7.4 lbs in a queen which is very similar.
The Sleep & Beyond is about 1.8 lbs/yd but uses Merino wool which is a breed that produces finer wool which is softer but would compress more (as you noted) and many manufacturers of wool toppers believe that a medium fine or thicker wool does a better job as a topper (vs a comforter).
There is also more about wool toppers in post #3 here.
There are also some topper guidelines in post #2 here and the posts it links to.
Phoenix
PS @ Mark in Texas …
This could be a very risky choice for many people who already had softer latex in the comfort layers of their mattress or were in higher weight ranges. I would always keep in mind that what works for some may be completely unsuitable for others and the goal is always to make choices based on what is best for each individual person and their unique needs and preferences.