From one of the longest threads in the AMG customer forums. These are among their most active and loyal customers (people on there have been buying Mercedes and AMGs for decades as well as the relatively new guys). I think our feelings on the subject are pretty obvious. It would probably shift even more towards "No" once you start badging a 4.0 liter engine with a "63". Now they can't badge it as anything less than 45 since that's what the 2.0-liter cars are labels. We'll see.
It's dumb. I COULDN'T STAND when the E46 3-Series came out and the badged the 2.5-liter the "323" so it wouldn't seem too close to the 2.8-liter "328" in numbering (328-323=5 vs. 328-325=3). Just man up and badge along with displacement. Like I said in the other reply: "It's like wearing a shirt that says you're 6 feet tall, when you are actually 4 feet...what does it matter if you are just as fast or faster?"