I've bought one of these, 2.0 GS4 diesel saloon, and very nice it is too! a worthy replacement for the 8G IMO.
size is comparable to an 8G, spec on the GS4 is excellent (leather, sat nav, music server, all the electric toys etc). drive is very sporty, handling is superb for a FWD car better than the 8G. Fuel economy is superb at 45 - 48mpg with lots of thrashing! The only downside I can see so far is the quality of door plastics looks quite cheap and plasticy compared to the 8G. I'm looking into whether the door cards and plastics can be retrimmed in faux leather or alacntara or similar to improve the feel and quality.