I think you can find some of this info. on their websites. Or call and describe what you want and see what they recommend. I believe Flobeds use talalay from Latex International. I think sleepez uses tatalaly from Latex International and dunlop from Latex Green. But they say they use a variety of sources, so you would need to check with them.
One main difference is that Flobeds uses a 2" convoluted pieces on top to add some softness (you can take off of course). Below that you can make as firm as you want. If you are getting queen or larger it will be split in the middle. So, you can make one side firmer than the other to have some options to play with. I think the flobeds cover is nicer as well.
I have in my notes for Flobeds:
Soft: 19-22
M: 26-30
F: 30-34
XF: 34-38
SF: 42-46
I believe the medium at sleepez is 30-32, so more like a flobed firm.
If you want fairly firm with soft on top from flobeds, you would probably have 2 layers of XF and the top being anywhere from medium to XF. They the convoluted piece would add some softness as well.
Everyone likes it different, so you really have to figure it out with trial and error. Both companies are pretty good for that because you can exchange layers to get it right or return the whole thing.
