Our booking engine at tickets.railforums.co.uk (powered by TrainSplit) helps support the running of the forum with every ticket purchase! Find out more and ask any questions/give us feedback in this thread!
I imagine the bogies are the only real bit of value - the structure of the coaches is such that they can't really be modified to be anything other than a sleeper carriage. I'm sure a ROSCO looked in to it when they became available originally.