I saw an interesting comparison between a X and non X thru the slalom course....
The X beat the non-X in the wet AND the dry.
So, depends on what type of speed you are looking for. straight line, or twisties
And, the above test makes me think the X might be a safer option as well.
If you are considering the S and you are going to modify the suspension, then you are only gaining the tighter seats. Personally, I did not find the S seats comfortable in the sedan. However, the the S seats in the coupe were more comphy to me than in the sedan. You really need to sit in both!!! (S & nonS)
If you are concerned about gas mileage....then you might want to look at another vehicle. None of the G's get great mileage.
I believe that the 09 with more gears gets better, however starting in 09 prem. fuel is required. Whereas with the 07-08 sedans prem. is only recommended.
I live just north of CLT and don't get enough snow, but when we do!!
based on
http://www.fueleconomy.gov
07 G35X 17/23
07 G35 17/24
09 G37X 18/25
09 G37 18/26