I go for looks and go, I suppose, not sound and go. I really like the CLS SB. I love the interior I had swapped into it.
It goes very well; the stock 550 bhp, and 530 ft lb or more torque between 1750 and 5500 rpm, is enough for most, including me; more than almost any M156...
How it sounds is not a particular selling point; distant thunder rumbles most of the time, suddenly much closer when you use your right foot a little. If it sounded like a wet fart, I'd have had the exhaust sorted; but it doesn't, so I don't feel the need.
My point is that some M156 owners seem to think the M156's USPs are the sound, and a twelve year old survey. Bit sad, that, don't you think...