Who can say with a Fuji camera, since I don't have a really 12m camera to compare with, I can only go with what I've got. I suppose in away it is a 12m camera since it uses two types of 6m to provide the extended dynamic range, which it does very well.
As for image quality compared to S2, don't expect any great jump although there is an improvement, having said that, the S2 has always been a great camera for image quality. As I have mentioned the jpegs seem different to S2, don't recommend adding to much unsharp mask, have only just got the hyper-utility software onto my Mac(must have 10.3 to do so). The quality of image produced from RAW is far superior to jpeg based on initial tests, the software is slow and a pain to use but results are worth it, but only use if maximum image quality is a prime concern, for general use for say PR or Press images, the jpegs are more than acceptable those avoiding to much time with post-production.