I keep the bass knob at 0 to 2, depending on the guitar, and have a stout shallow V shape for the graphic, with the center slider being neutral to preserve more mids. I guess I should call it U shape.
Another absolutely critical item for the MkIII is the treble knob. Sounds great for high gain when set at 8+ (which increases gain), but then you have to back the mega-powerful Presence down to ~3-4, and the clean channel suffers. I reduce my treble knob to 6-7 and have the Presence at 5 and R1 volume at 7.5 and use more Lead Drive to make up for decreasing the treble knob. Even with my EMG 81/85 equipped metal guitars, I can get a full range of good cleans (guitar volume knob reduced) or all-out blistering metal. With passive pickups, the clean sound is truly excellent and of course high gain rules also.
It is a fine art to tune your MkIII to your actual rig, but once it's done, it's a thing of absolute beauty.