Hi Ilovemywillow,
Perhaps not surprisingly … I do have a few comments about this mattress 
The ILD’s seem suspiciously low for natural Dunlop although there are new foaming methods being used which can lead to softer versions of Dunlop latex (and they didn’t answer the SBR part of your question).
There is only 5.5" of latex in the mattress over the polyfoam core.
For this type of construction … the price is very high compared to higher quality mattresses that are offered by other manufacturers and outlets for significantly less. Post #21 here has a list of the members here who specialize in selling online, offer good knowledge and guidance, and will give you many much better quality/value choices.
In addition to this … the only way I would make a purchase from an outlet that knows little about the mattresses they are selling (and likely has little idea about how to fit a mattress to a person over the phone) would be if I was willing to “roll the dice” and buy from an outlet that offered a 100% money back guarantee (including shipping). According to the Sears refund policy … you have to pay the return shipping and a 15% fee for returns. For me … this and the lack of “mattress knowledge” would exclude them from consideration unless I knew for sure that the mattress was perfect for my needs and preferences and there was little to no chance I would want to return it. Even here though … the price would put it out of contention for me.
As an example … a higher quality “all latex” version of the blissful is being sold here which apparently includes 4" of talalay and a latex base for much less.
Overall … this is not a direction I would personally consider because the price and the risk would both be way too high.
Phoenix