hey lester,
interesting...i've not played an original CII+, but i've got something perty close to a good speed metal tone going on the C channel. I dig the MkIV mode too, but it's more bassy and gainy than the C...the way I play (i've got an obscenely heavy-handed pick attack...my strings hate me) it's too much for a trip down Master of Puppets lane...but i'll take your advice and mess around with the IV.
btw, how do you like the mesa thiele cab? i wanna play the MkV out of an extension cab to minimize some of the shock to the 'brains' (got a combo) and the port seems interesting
cheers