Think it will be lighter?If S650 is heavily based on S550, and still features a n/a V8 engine (I'm pretty sure the hybrid will only be an option in the US and the V8 will still be available) and I'm confident it's going to be a better car than the S550. Looks will be subjective, but as a driving machine, it will be an improvement over the current car, just as S550 was over the S197.
By all means, it probably will be improvement. Lets hope so. lol
But for me it might not be enough to get one.
That's why I got a S550 over a 13-14 GT. The S550 is improved from the inside out over the 13-14 GT.