We were really excited to get the sleeping duck after reading the reviews but I have to say my partner and I both suffered terribly from the get go. We previously had a $500 sultan from Ikea which was actually fine for 8 years (I am 38 and 50kg, he is 35 and 75kg). After a month of trying I took to sleeping in my sons room as I just couldn't handle the pain.
SD were amazing cust service though, they sent their firmer topper to trial but it was also really bad (perhaps slight improvement on the original med-firm). But then when we really couldn't manage it they actually picked everything up for free so the final charge to us was nothing.
Could not fault their friendly and fair cust service but wow yes the mattress I couldn't recommend and unfort this review site is on the products.