The biggest difference is the fact the shells are old. Plastic does not last forever, so they will become more brital. You may never have a problem or you may crack them first day. Thats the issue with old boots there are usually no warning signs that something is going to go wrong.
Other then that they will be pretty much the same, but you would be better off going to a bootfitter and have him decide the best boot for you. It may even be a full tilt.