I think the rougher and quicker the clutch shifts, the less wear. The clutch is not "slipping for comfort". Of course, this theory is based on the same driving style. If you drive agressively all the time with the highest sport settings, and make more shifts, the clutch will wear out faster than if you drive normally using the "slush" mode. Driving normally using the highest sport setting should be the best clutch life.
Clutch wear is a function of the duration of slip and the amount of torque and speed put through while slipping. I bet that heat buildup from prior shifts greatly exacerbates this. LC is an extreme example where for a relatively long duration at the start you have slip, with a very high speed differential across the plates, and with maximum torque, and then followed by highest speed/torque shifts.
The higher SMG modes, while short in slip duration, have a high speed differential across the plates because they don't attempt to speed match, though the throttle-lift technique will mitigate this. Full throttle shifts in highest modes should produce signficant wear.
I suspect that least clutch wear occurs when launching slowly, and using mid-level SMG modes with throttle lift on shifts.
There was an article in the german AMS (3/2005) about M5 settings. They took their fastest lap on a track with S4 and comfort if i remember correct. Maybe someone around here has the article. :M5launch: