The vignetting is just the fact that we didn't zoom in to cover overscan. Other than light falloff, you'll find that the "dreaded" vignette, is just a result of not zooming in on the GG enough. What looks good on the cam's LCD, is not enough. If it was going to DVD, you could leave it, and no one would ever see it. Online video is different though, as there is no "safe" area.
My 50mm does show some barrel distortion...I have a 28-70 that shows none. It could be the macros, but I know from charts that the Minolta F1.4 does have some barrel distortion.
None of the footage through the cheap macros is as good as the GS400 stuff..even on the XL2, and DVX. Tomorrow I'll have 16:9 24P from the HVX, no macros, so you'll have a very good idea on the image quality from a full frame progressive image.