I did a lot of research and bought a King size Eva mattress for our existing timber slat base. It doesn't have the re-zonability that Sleeping Duck has, but the Eva is an incredibly comfortable inner spring mattress with cool foam topping. Somehow it's firm yet soft at the same time and I have never slept better. My only caveat is that it is heavy to move. We love our Eva and it's half the price of Sleeping Duck.

I second Andrew-Morriset’s opinion. The Eva is “somehow” firm+supportive yet soft+comfy, and half the price of the Sleeping Duck. Sleeping Duck’s customisation isn’t high on my priority for I don’t think I am the “princess and the pea” kind of sensitive sleeper (but am curious to know how others find this aspect of the Sleeping Duck!). Admittedly, I have also considered other very closely-competing mattresses like Sleep Republic, Sherman, Macoda and Naptime, but being on Jobkeeper meant that every multiple of $50 I can save counts... and so it was the Eva when it came to how much I could save while balancing getting the best possible support/comfort/quality for a mattress. Eva’s hefty weight doesn’t bother me - gives me a good reason to maintain my physical strength and mobility! HTH!

Strong mattress! Stiff edges when sitting. I don't see any problem storing mattress on side.

the Eva mattress is about 35cm thick and very firm. It would be fine on the floor if that's comfortable for you. (It would be too low for me). You don't need to flip the mattress as the memory foam is on the top, just rotate it every few months (turn it around so you swap the head end with the foot end.)

Keeping any mattress on the floor will lead to mould as there is no aeration on the bottom.