I'm hard pressed to think of any corporation that would take a migration script and run "as is". You will at the minimum have some standard code or comment block to put at the top and bottom of a script.

For example, in our particular place, we check the DB version before running a script (header), and stamp a version on success / error handle (footer).

We also have special statement which we need to put after each batch (where the migration currently places a "GO").

Needless to say, having to manually do this is time consuming. So my suggestion is the ability to customize what goes at the top, bottom and after each batch (GO) on the migration scripts. This would be a huge time saver.

If you are already allowing this, great (I am unable to join your beta as I'm in an agile dev team).