I'm not convinced that the first refresh of the S550 will be in its favor. Even the S197 - IMHO - looks best in its original 2005-2009 design. The chunky, open front end may not be the most aggressive, but it is very cohesive with the design and styling heritage.
Same applies to the back end, even though the design is WAY too heavy for its own good. Saleen's tunnelback rear end improves on this, but at the expense of adding too much length and bulk to the lower valance.
I didn't particularly care for tapering rear end on the 2010-2012's when they came out, but it did take some of the bulk off, stylistically. I started to accept the redesign until someone in the styling department ruined it in 2013 by sharpening the corners of the taper and putting center blackout trim in that area - effectively making a huge U shape in the middle of the car (making it look taller and bulkier than the 2005!)
While the S550 will probably be best 3 years into its run - more than enough time to get the kinks out - you'd probably be best off waiting for the '16s. Improved engineering (we hope!), lower dealer sticker price.
-Kurt