Yup. Did all that from the get-go. Ok here is what I just did.
Went into Painter 11. Imported Photoshop workspace (my preference). Then I dragged and dropped my old brush folders in as described in your link above. All worked in Painter 11. Then I exported the workspace. Went to Painter 12, imported the workspace and all brushes worked. Exited Painter, came back in and immediately got an error about a missing category. After that only the Painter 12 brushes worked. So I am back to square one.

I think Painter/Corel is just riddled with problems like this. I have been using Corel since Corel Draw version 5 (on and off) and they just never seem to get proper QA going in any of their work (although Corel Draw seems to be improving). I wish to god that Photoshop had these brushes. The so called natural media bristle brushes in PS are just a joke compared to Painters, but then in Painter I seem to spend 50% of my time fighting the app.

Guess I will manually delete the bogus folders Painter inserts when I need to access those brushes. And I will be praying for big strides forward when PS CS6 comes out in 2012.