Hi yianni54,
They both offer this same option (Although sleepEz doesn’t charge extra for it) and I would base whether you choose it on the suggestions of each manufacturer during your more extended conversations with them. In a 4 x 3" layer mattress the deepest layer has less effect on the feel and performance of the mattress for most people than the layers that are closer to the person on the mattress.
As I mentioned in my reply here … once you are down to final choices between “good and good” only you can decide on the “real” difference between them based on all the objective, subjective, and intangible differences between them that are part of any mattress purchase, including your more extended conversations on the phone, that may be more or less important to you. At this stage there is no “better or worse” and anything you choose will be among the best quality/value in the country.
As I also mentioned before … Both offer the same latex as FSF uses although SleepEz has other options as well. FSF offers organic Dunlop and 100% natural Talalay. SleepEz offers orgainc Dunlop (from the same supplier) 100% natural Dunlop (which is from the same supplier but lower cost), and 100% natural and blended Talalay latex from two different suppliers (including Latex International that FSF uses).
You can read one member’s comparison of the two cases in post #5 here although I believe that SleepEz may have changed their cover and now use a slightly stretchier cover than they were at that time.
Final choices are often the most difficult part of all but in the end only you can know or decide which is best for you.
Phoenix