I have a ROM burner so I always upgrade to the latest version to take advantage of any bug fixes. There are a few instances where you have to upgrade, such as with Jurassic Park. In Jurassic Park, they changed the way the T-Rex's right/left motor works to prevent gears from stripping. But usually there is no reason you have to upgrade except for wanting to have the latest version and its fixes to any bugs and rule changes.