I've been trying to do a spec for a PowerBuilder 9 to 11.5 migration of a relatively complex application. Granted PowerBuilder is not really my specialty I'm having issues trying to justify an estimate for this part of the project (and the PowerBuilder people I've been talking with have had some personal issues lately and are out of communication). These are some of the metrics that we have seen and can evaluate:
-PBL Files
-Main Windows
-Data Windows
-Functions
(no we don't have the source available on this project)
What metrics in particular are helpful and how long would any given "unit" such as a Data Window take?
Most PowerBuilder migrations are rather smooth. The biggest thing that might get you moving from 9.0 to 11.5 are (a) the change in the Rich Text Edit control (if used) and (b) Unicode versus ANSI. The later will primarily be an issue if you have external function calls that pass strings, and only require the addition of a ;ANSI suffix or a migration to the Unicode version of the call.
So, look to see if the Rich Text Edit control is used, and look to see how many external function calls are declared. If you don't have any of either, it would be as simple as opening the project up in 11.5 (after making a backup of course) and allowing 11.5 to do the migration.