Ikon Deluxe OC is considerably milder than any of the ATT baseplates. The mildest of the ATTs are the M1 and M2, so they'd be closest. (I happen to put them right next to each other, so comparing OC to OC, you'd want the M2. According to the latest polls, however, I'm in a sizeable minority; but majority of folks rank the M2 as slightly more aggressive than the M1).