Many many thanks to all of you who gave me your feedback when I asked if the Ikea Stockholm Sofa is comfortable. The resounding answer is (not so surprisingly) - no.
As Marco stated - when you go to Ikea stick to the hard things.
I went and sat on a Stockholm (and a few mattresses) and even my overflated ass hurt.
Thank you so much for the advice, you saved me from antagonizing ass misery :)