Hi Nowhisky.
I am glad that SleepOnLatex helped you with the return, they do indeed have a very good customer service that I think very highly of.
Mid and upper back issues can come from several sources. In the case of the upper body then good horizontal alignment is important but lateral (side to side) alignment is also important. In your situation as the back issues are also combined with the numbness of the arm this is probably a case of needing to sink in a bit more and have a plusher sleeping surface to relief the shoulder pressure points. As you did not chose the ultra-plush version of Shovlin mattress as you were advised a year ago you then you most likely need to probably the topper. You can perhaps try a softer Talalay of 19ILD or so (it has a plusher feel than Dunlop in the same ILD) I am not very sure if you did not like the thickness or the Dunlop but as many people prefer memory foam for a softer comfort surface you can have a look at a few other topper options.
There is more information about choosing a topper and a link to the better online sources I’m aware of in post #2 hereand the topper guidelines it links to 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.
I am not very sure that in looking for extra-plushness you would want to select a wool topper. Wool can be an excellent choice but depends upon what attempting to accomplish.
Depending on your preferences both latex and Memory foam can be good choices to add extra plushness to your existing mattress.
[quote]…
Nirvana Specs - Basic topper included with bed purchase which is of questionable quality[/quote]
I cannot comment upon why you would call the topper “questionable” as you did not replay to question earlier in this thread about what material, ILD & thickness of the topper.
Phoenix