Hi npfd,
If you’ve read the tutorial post it’s probably pretty predictable what I would say about both a Simmons and a Kingsdown mattress.
It’s unlikely that you will be able to find out the quality of the materials in either mattress (which are most likely in the lower end of the quality/durability range) and without this information (in the comfort layers especially) you would be making a very risky purchase with either one.
The innersprings aren’t normally the weak link in a mattress or the most important part of the durability of a mattress (a mattress will soften, compress, and break down from the top down) and which one would be “best” for you depends on which one your testing indicates is the most suitable choice in terms of PPP. Any “sagging” in a mattress is almost always from lower quality foam layers and materials above the springs which is why it’s so important to know their type and quality. Even worse than visible impressions are virtual impressions where the foam has softened without losing height (which is more common than visible sagging) and you end up losing comfort and support and need to replace the mattress and a warranty doesn’t cover the loss of comfort and support. In some cases, if the mattress is on the edge of already being too soft for you, this can happen quite quickly in a matter of months.
You can read more about innersprings in this article and in post #10 here.
As I mentioned in my previous replies … I would avoid both Kingsdown and Simmons or any other mattress where you aren’t able to find out the quality of the materials inside it.
Phoenix