Like Matt, i've been lucky enough to have had both, and I too have gone GS to GTS and back to GS? Prefer the performance of the GS as, for me, it is a better balance between sports car and GT car (even the GTs MC Shift), its more nimble and chuckable. Lookswise, I love them both, the aggression and sharper edges of the GTS are more contemporary, whilst the GS is a more classical shape I think, It will be interesting to see which is regarded as the better looking car in 40-50 years when they will both have the potential to seen as iconic Maseratis of about the same era.