OTM (Oracle Transportation Management) can be a big dilemma if we are moving to cloud or upgrading. It is a configurable system that allows customisation from small degree of change to major one. A major part would be your decision to upgrade or migrate to cloud from the amount of configuration or customisation done to OTM.
Many organisations would prefer to migrate to cloud for future support and upgrades. separate the customisation Cloud, like its name, really is cloud. You cannot foresee what will happen in Cloud until you are in Cloud. Your risk appetite will need to be high if you have done a lot of customisation on OTM. Prior your move to Cloud, a major task is to separate the customisation into REST services. How much time and effort will you invest? Should you forgo your customisation instead?
Upgrading OTM major version can be quite a slow painful experience. The 6.4.3 is the last available version that is non Cloud based. The decision not to move to Cloud usually lies with the amount of customisation done. The biggest changes from old version to 6.4.3 version are architectural, user interface (UI) and report server. The dilemma comes in the sequence of upgrade you want to take. Report server is now mandatory after the removal of embedded reports. Should you move your embedded report first or do together with upgrade? How much training period should you allow for the new UI? How much time will it take to fix your customisation during the upgrade?
OTM upgrade or migration to cloud is a painful dilemma. There is always a temptation to status quo the version due to the massive efforts to factor risk and change management. In many cases, you need lots of patience and alternate plans while you are upgrading or migrating.