In my scenario, I really want to have a roll-up summary in my master object so I can know which ones doesn't have child objects. Currently it is a lookup relationship which is required and will be automatically deleted if the parent object is deleted.
So from my perspective, I really don't see any difference between this kind of lookup relationship to master-detail. However, it is production so I need to be extremely cautious here. Should I feel safe to change the relationship here?