[curt.clifton]

Yours seems like a fairly unique migration path, so I'm not surprised the Help documentation doesn't address it.

I'm not entirely clear what you mean by "metadata attachments". Do you mean that the notes of the items in OmniFocus have the "Metadata" text you listed?

If so, I can think of two likely ways to purge text. One would be on the export from Brainforest. Is it possible to tell it not to include that information? The other likely approach is to use Applescript to delete the Metadata lines from the notes. If you want to pursue that approach, I'd suggest posting to the OmniFocus Extras forum. The AppleScripters hang out there and someone might have a ready solution.