Personally I like the MXR 78' Bad Ass Distortion A.K.A. Appetite for Distortion. The MXR Bad Ass Modified O.D. pedal is not bad but sounds a bit "boxy" through my Hot Rod Deluxe. It is a great pedal... just not "my tone". It might make a nice lead boost over and above the tube gain (like a Tube Screamer but voiced differently)? The MXR Full Bore Metal is PERFECT for someone looking for Modern High Gain from Enter Sand Man to full out Death Metal. It is fun to play with but not a necessary "color in my personal Crayon box". I would definitely have one if I were a Metal shred guitarist.
Come on down to Rock Bottom and test drive them for yourself. The price for these are lower here than any place else...guarenteed!