Spring Equivalent to Poly Base?

Hello.
I’ve done quite a bit of reading on this site, so know that I’m asking with ‘some’ knowledge. My wife and I found this mattress that we mostly liked, with a 8" poly foam base, 2" memory, 2" latex on top. More details here if you’d like: Jonathan Stevens Concerto.
What I’d lean toward is something like the Bolsa Spring, memory foam, then 20d latex. Partly because I think we might still be okay with coils, it might breathe more, and cost a little less. Being an engineer and working with furniture, I do love the idea of latex and coils for a longer and more consistent life.
Do you think something like this custom setup I mentioned would be somewhat equivalent?
(Also, the other mattress we loved was a Beautyrest Black X-Class, but that’s way more than we want to spend.)

Thank you for the questions. The bolsa is a great spring and we now carry a very nice memory foam that feels more like latex in the fact that it’s much faster recovery than conventional memory foam and it’s open cell which means it breathes better also. It’s called Hypurgel - Latex Mattresses On Sale - Latex Mattress Toppers - Phoenix, AZ Topping that with latex should give you a similar yet better feel than Concerto or Black and last a lot longer as well. Plus with our zippered cover you have access to make changes down the road if necessary.

I guess if memory foam is firmer than 20-25 then at least the progression is correct. However, if memory foam is more like tempur (slow recovery), would it really work with bouncy latex on top? When you change the position, there will constantly be temporary empty space between the two layers.

By the way, Pure Latex in Concerto is obviously not 100% natural latex, but a hybrid with probably about 70% poly foam and 30% latex.

Good point! I know about the difference between natural and others, but I didn’t gather the “pure latex” until you mentioned it. Thank you!
Yes, there could be potential for a temporary air gap whenever putting latex over memory, but I can’t imagine it would be too unfavorable.

Personally I’m not someone who would mix memory foam with latex but some people like the feel of the combination and the option to put either one on top to tweak the feel.

Can you tell me the actual density of the HyPurGel you sell? It seems to have a comment in the image for the pdf specs.

It says between 2.7 and 3.3 density. 3.3 would be the 25 ILD and 2.7 is the 15 ILD.