I drove the 997.1 and 997.2 back to back with the M3. I liked the .2 engine better than the .1, had significantly more power but I felt that the S65 had a slightly better throttle response. Not by a huge margin, but the advantage was there. I also thought it likes to rev more than either of the Porsche engines and was smoother in the process.
When talking about fuel economy, I hope you guys are taking into consideration the huge weight difference as well as the aero considerations. Is the Porsche engine really more fuel efficient or just powering a much smaller/lighter car? We'll probably never know?
Considering the price difference, I think the S65 is an incredible achievement. I think if BMW had dropped it into a 3200lbs chassis they would have killed the non-GT3 performance wise. I'm a little bummed that they didn't and that they show no intention to compete in this category.
Anyway, I loved how connected to the driver the 997.2 was and how direct the steering and transmission felt. If I could justify the $30,000 price difference, I'd probably buy one - then again for that much money I could simply buy a used Cayman and turn it into a much better track car than either the 911S or E90 M3, all the while keeping my bimmer.
2015 F80 ED
2004 Z4 3.0
2014 X3 35i