As briefly mentioned above, the E-Diff works by utilising itself and DSC, by braking the inside wheel (rear obviously, being RWD!) under power-on cornering to prevent excessive, pointless and embarrassing inside wheel spin!
So, OP, it depends on your driving style! If you like to put your foot down through corners (and which BMW driver doesn't?!) then the E-Diff will do it's job to a greater extent, naturally leading to more wear.
Depending on to what extent, you may or may not see the DSC light flashing on the instrument panel.
DSC does, to a small extent, work in the background without notifying the driver.
Also, traction loss and DSC intervention will increase brake wear, again, depending to what extent and what conditions.