Yes, the updated M279 V12 in the SL65 AMG has more power and torque but the car also weighs about 230 pounds more with the majority of that weight coming on the nose. Is the weight penalty worth it? According to the handling and acceleration data from Car and Driver, no. The 1/4 mile comes by 11.8 seconds at 124 miles per hour. In other words, basically a wash with the Performance Package SL63 AMG which is lighter and $60k cheaper. Ouch.
AMG updated the V12 but it's still a relatively ancient design. Low revving, SOHC, and just a stump puller versus the lighter, higher revving, and better breathing M157. BenzBoost hates to say it, but, the SL65 AMG just does not make sense any longer. Grab an SL63 AMG and save the pocketed change for some upgraded turbos. You'll have a more powerful and more fun car to drive.