Dimitri Furman discusses the MAXSIZE property on an Azure SQL Database:
Customers can use this ability to allow scaling down to a lower service objective, when otherwise scaling down wouldn’t be possible because the database is too large.
While this capability is useful for some customers, the fact that the actual size quota for the database may be different from the maximum size quota for the selected service objective can be unexpected, particularly for customers who are used to working with the traditional SQL Server, where there is no explicit size quota at the database level. Exceeding the unexpectedly low database size quota will prevent new space allocations within the database, which can be a serious problem for many types of applications.
One more thing to think about, I suppose.