Hey yeah, I actually had a harder time with that shape too come to think of it...I went with the form that uses the ring finger spanning the 3 inside notes, then angling up enough to let the barred high E string ring out. Perhaps harder at first, but once I had it, it was easier to hit quickly versus using all four fingers.
[FONT=Palatino Linotype]"Bust a nut!" - Dimebag
"Imagination is more important than knowledge." - Einstein[/FONT]