Cool, I'm glad to see this thread resurface. Since this posting, "Ugly Red Bastard" (as I've affectionately named him) has taken a permanent position as my resident snare bottom mic.
And he works wonderfully in that regard, giving me exactly what I want from the bottom of the snare.
It's a neat modification, just be aware that a '57 will no longer be a '57 once you have performed this mod. It won't sound the same, and it won't give you the sounds that you usually use a '57 for. It becomes a different mic, but still a good mic, and pretty useful.
-Lance