With polyfoam I would consider a minimum of 1.8 lb density as being suitable for a support core and you will usually find it in the range of 1.5 lbs to about 2.5 lbs (although you will occasionally see densities both higher and lower than these). 2.0 lbs is in the range that would be perfectly suitable and is actually higher quality than many of the much more costly mattresses made by major manufacturers use (you will often see them use 1.5 lb polyfoam which should only be used as a base layer in lower cost mattresses). 4 lb gel memory foam is usually the norm for gel memory foam although I would want to know if it used particles or was infused as a mix of gel and memory foam but with only 1.5" of the gel memory foam this wouldn’t matter a great deal either way. Overall this doesn’t appear to have any obvious weak links
In most cases 2 - 3 zones are about the most that is really needed (if zoning is even needed at all) … particularly with latex which has the ability to adapt to different weights and shapes because of it’s elasticity and compression modulus (gets firmer faster with deeper compression). In a single zoned layer … the difference between the zones are often not significant enough to make a real difference anyway. So while I wouldn’t consider it to be a “negative” (it wouldn’t usually make the mattress worse than 3 zones) unless the zoning was detrimental to your particular body type and sleeping position … I wouldn’t consider it to be a particularly meaningful benefit either. If you have tested it and it provides you with good PPP (Pressure relief, Posture and alignment, and Personal preferences) then it would be fine … even though I wouldn’t “add value” because of it.
If you look on the Golden site, there is a Reflections Latex Eurotop here and you will see it talks about polyfoam in the quilting (and you can see that it is quilted) and in the core. If you look at the 6" Latex Reflection here … it says that there is only 6" of latex over an 8" polyfoam core and it doesn’t have any quilting so the latex is on the top of the mattress and this would be all the layers. I would make sure what any mattress you are looking at really has in it layer by layer and which version you are looking at and it’s the job of the retailer to confirm this for you so you don’t have to go chasing down foam specs or phone the factory to find out.
Neither of these have any obvious weak links (assuming that you have the unquilted version of the Reflections).