If your Profiles folder is gone you only lose your single player progress, retriever module assessment and 5 custom classes to default which can easily be set up again. The others will be there.
True, its not as dire as I made it sound. The effect on assessments goes beyond just retriever (which Is bugged on its own, as I recall). Weapon unlock counts often get out of sync, for example.
Rank, etc. and all usage data are successfully stored in the cloud, but all of those assessments apparently arent rebuilt properly at the beginning of each session. This matters to some folks, not at all to others.