leaving the upper deck also give the option of carrying 100-150 passengers etc.
One for the experts but maybe one objection to that is once you mix freight with passengers you start placing limitations on what freight you can carry due to dangerous goods rules etc. For example Internal Combustion engines (even new) are banned as hold freight on pax flights by many (?all) operators, similarly even small amounts of radioactive materials e.g for medical use are banned....). That might be in part what possibly contributed to the demise of the various "combis" in the first place.