I get where Blake's coming from. With the C+ I've had in the band mix, when working the 750, the line between "too much and it's boxy" and "I just disappeared from the mix" is razor thin. All marks can accomplish this with the 750, however with all the others the line is not so hard to find.
Tom I agree with you in the clarity & feel, however as to harsh, while some have more of a tendency (cough III) I beleive this really comes down to amp to amp variance. I'm really sensative to "tinnitus from harsh" and this is the first thing that will send an amp packing for me, and with all the other Marks some are better than others. Example no/black are less likely to have it, and this blue '99 I have now is damn near C+ level just with a bit more III grind. I've only had one IVa but it was more harsh as well.