Millbrook Memory Ortho 1400 mattress

Hello chaps, Thanks for your very informative website. I hope you can help me: We recently refused delivery of a Millbrook Memory Ortho 1400 mattress as we couldn't get it upstairs and, apparently, it wouldn't bend as it was too firm, so to bend it may have been to damage it. I am now looking at less firm mattresses that we will be able to bend a bit, but I'm concerned about damaging it before we get to sleep on it!

Currently I'm considering the Breasley Flexcell Pocket 1600 37degree. It's identified on the website as being medium-firm. Are you able to advise on whether it would be ok to bend this mattress a bit to get it up the stairs?

Many thanks, Richard. .