Please take a look at fmdiff.com which may serve you well.
Currently layout details and possibly a few new FM12 functions are not yet listed.
Thanks for the advice, but for the moment, I'm looking for a deployment tool, more than a debugging tool. It looks pretty useful, and will give it a look.
What I normally do is set up a series of scripts that do three tasks:
1) Find all records in all tables that need migrating.
2) Delete all records in all tables that need migrating.
3) Import all records from one copy of the database into the current file.
You run script (1) in the old database (once you take it offline). You run scripts (2) and (3) in your new version. Then you post your new version to production.
There are also some commercial tools that can help. Goya recently released one that looks interesting called RefreshFM; check out http://www.goya.com.au/refreshfm. I haven't used it myself, but it shows promise.