Hi kchurch2213,
Viscosoft is a small imported memory foam mattress and pillow line that has been in business for about seven years. The foams are made in Hangzhou, China. I would read post #6 here about mattresses and foams imported from Asia or China and which may have been compressed for long periods of time in either shipping or storage before being purchased.
While I personally don’t have any experience with Viscosoft, there are perhaps other more knowledgeable site members who are familiar with them and they can share their information.
I’m sorry but the specs don’t look especially good to me. The Muse has an 8" polyfoam base that is 2.0 lb., which is a good density. The next layer of 2" of 4 lb. memory foam is the minimum I recommend (and for someone above 200 pounds, which I believe you mentioned applies to your household, it is lower than I would recommend), and the upper 2" of 3.5 lb. memory foam is lower than I would recommend overall.
As a refresher, you may wish to take a look at the durability guidelines here to make sure there are no lower quality materials or weak links in any mattress you are considering. It is nice that they are responsive to your emails.
Phoenix