Interesting, and I’ve had a similar experience.
But, I will say, that pillow top we had from Simmons originally was the best bed I’d owned. It was so comfortable.
We figured, for the mattress alone, we got good utility from it for only 1.5 years. It had a spring base that didn’t degrade.
What did you learn about those box springs?
Too springy : )
I like a medium firm leaning towards firm.
The spring wire foundation just made the bed softer.
If it was not for that sag the mattress is good medium firm.
It is a Stearns and Foster Hurston mattress.
Does Stearns and Foster sag?
Image result for stearns and foster hurston mattress sags
Stearns and Foster mattresses are innerspring and hybrid. Though they use high end materials and use authentic craftspeople to manufacture their mattresses, there are numerous reports of the mattresses sagging over a short period of time, especially their lower priced collections like Estate and Lux Estate.
https://www.slumbersearch.com/stearns-and-foster-mattress-reviews
VERY expensive below like $4,500 and $5,000 to over $6,000 !!
https://www.us-mattress.com/stearns-and-foster-reserve-mattresses.html
The Reserve Collection is the highest end mattress offering by Stearns & Foster. It offers a similar feel to the Lux Estate Collection, but has an extra foam layer and an extra pillow top option for added softness. Another layer is added below the gel foam for an even softer profile. This mattress is quite expensive, but at 16’’ for the pillow top has a very high profile. This top of the line mattress doesn’t have as many negative reports about durability, which is a big win for customers. Rare complaints mostly mention firmness issues.
_______________________
I have tried this inexpensive bed. It was too bouncy and soft even though it said medium firm. I returned it and Amazon said keep it or give it away and they returned my $282 money!! A neighbor of mine grabbed it so it worked out for them : )
https://www.amazon.com/gp/product/B09GLVN58R/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Made in Taiwan or a place like it. So it is shipped all the way across the ocean and the mattress seller makes a profit so how much do the $1,500, $2,000 or $4,000 and $6,000 mattresses cost to make?
Big profit I suspect.