If you are over 12 stone the open sprung one won't last and a heavyweight person might even feel the springs. Go for pocket sprung at least because you can't upgrade the mattress later as with a normal bed.

I am in the process of buying a sofa bed online and am trying to work out what mattress to get - the open sprung mattress is included in the price, but there is an option to get a memory foam or pocket sprung mattress at extra cost - do you think the open sprung one will be adequate for occasional use?

Thanks for your comments in advance!