Does replacing the mattress in a sofa bed make it more comfortable?
I have a traditional sofa sleeper that is very uncomfortable. I have seen a number of mattress replacements on line that offer memory form, are part air mattress, or just claim to be better than a traditional mattress.
I am concerned that the bed is uncomfortable primarily because of the bed support and no matter how good a mattress I get it is still going to be uncomfortable.
Has anyone had experience replacing their sofa mattress? Did it help? What kind did you get?

A softer mattress will definitely help. Sleeper sofas never have been my favorite.
It really didn’t help mine at all comfort wise.I did replace the mattress on mine that came from the manufacturer with a memory foam mattress and it was sincerely just as uncomfortable as the original. Good thing I got a 30 day “sleep trial” with a money back guarantee because it was expensive and I knew within a week of taking it for a test drive that it made little difference. You are right, the comfort factor is in the mechanism and support underneath the mattress. Unfortunately, sofa bed mattresses must be a certain height in order for the bed to close into a couch. That being said, you still feel that support underneath a replacement mattress because your body weight compresses the mattress content and you still feel like you are sleeping on railroad tracks.
why not invest in some foam pieces to put underneath and on top of the mattress before buying a whole new mattress. the one you put underneath may help with the bars, and still be able to fold up into the couch. the top one may not fit when you close it but just put it on when guests are ready for bed. they have those nice ones that are shaped like egg carton
we put a futon mattress on ours, worked out really well