Well be thankful for the DC's VGA capabilities! Sheesh.. DC games look good enough on HD TV's imo. Let treasure do a HD remake of radient silvergun or gunstar heroes and then we're in action.
I own the DC version of Bangai-O, but personally I could never get into it. It just seemed really tedious and repetitive. Maybe I didn't give it enough of a chance, though.
From what I remember Bangai-O is one of the only DC titles that will not work correctly with the DC VGA adaptor. Even if you do that swap cable trick. I seem to remember it only filling a small section of the screen.