The _QI_ used to pick either _ADD_ vs _UPDATE_ based on the return type, but it was too buggy in many conditions.. it just isn't a safe assumption, for example you might have the data in a non-local CacheStore which hasn't been state transferred to the current owner yet. I certainly agree that it can be improved, but it's tricky business to keep it in synch for for now we opted for safety: always use UPDATE. The new flag is meant for those advanced use cases in which you (app developer) just happen to know it's new data, like the initial import of new stuff.

I'm not arguing that this Flag needs to be the definitive way on how we want to solve this problem, but it's imho important to have the switch available so that we can suggest using it when needed.