Within the functionality you can add a piece of code before, during and after a upgrade script, this is really usefull with data converisons, really like the functionality.
But what I am missing is when I add a new function and need this function in the data conversion there is no place I can do this except for the manual script. But the manual script I have to delete after upgrading, otherwise this will be executing every upgrade.
It would be usefull for me if we are able to make a upgrade script functionality but the really in the end which we can assign to a certain upgrade version x → version x.y