Relax, just try it out for a few months, you can return it easily. I had the old gen and it sagged badly after 5 years. They replaced it with the new gen which is holding up. But I'll probably go for a spring mattress in a couple of years. Spring is still nicer than the best foam.
Lots of people describing the duck mattress as like a cloud. I prefer a firmer mattress so the duck wasn't for me. Not even the extra firm mattress was firm enough. Got rid of it after about a month.
ours has dipped but it's nearly 6 years old. we had a single koala for a month in the guest room and it was a different design... So it's hard to compare apples to apples...
We have sleeping duck and we like it. We have been rotating it but still have a divot on my partners side. The mattress height is my biggest complaint. I have deep sheets from the US which work - had to have someone bring them because I couldn't find deep enough sheets that we liked here.
Ordered a sleeping duck in firm, I ended up getting a free switch for my half of the bed to a medium firmness as I am a side sleeper and we've love it since! It's been almost 7 years now and it's still going strong.
alpacaccino
