I don't "lament" these things, glad I did what I did when I did it. I think you got a great deal, myself.
It's going to be awhile before I can seriously look at that 12mm f2 but every picture I've seen done with it is sharp and clean. It may not be necessary for me if I can live with the 12mm end of the "kit" lens that I pre-ordered the Olympus OMD E-M5 with.
The Lumix 14mm f2.5 and the Lumix 20mm f1.7 are also SUPER lenses to use on both the GH2 and the Olympus Pen's. I've got both of those and the 20mm has been on my GH2 most of the time while I've been getting used to the GH2 menu structure.
One thing I really like about both the GH2 and the Pen E-P3 is that people don't take me as seriously as they do when I walk around with a big Canon 7D, 60D, or any other "largish" DSLR. I can look so much like a tourist nobody really "messes" with me, which lets me get still images and video almost unnoticed.
You'll enjoy yours.