No, it's 15% for all CM's. Our DD is a WDW CM, and although it was 25% up until sometime this summer, it's now just 15%. Still, the 15% is off of the full price (not the discounted price). So AKV, at $104pp - 15% = $88.40 (and another $8 off for 100+ points makes it $80.40pp). One other advantage for CM's is that they don't have the 160 point minimum buy-in.
It has been rumored that all CM discounts for DVC will be going away soon. But for now, at least, it's still there.