#1
I currently have a boss os-2 ds/od pedal, and its pretty sweet. but now that im getting better and i want a new range of sounds, i want to split this into 2 separate pedals that do each better. for ds i was looking at the digitech metal master. i listened to some sound samples and was impressed. i will be going shopping this week so any suggestions on what to test out? thanks all.

i play mostly metal, so ds should take care of metallica/pantera/nu metal styles, and the OD should handle led zepplin, hendrix, classic rock.
#2
For the distortion, the Electro Harmonix Metal Muff would be a much better choice than that Digitech that you're looking at.