I think most lower bar sets fit both the pre '08 and '08 GS models, however it is unlikely that any upper bar sets will fit and additionally I believe most of the bars are not compatible with the Remus exhaust headers as the lambda sensors' position on the Remus fowls with the bar mounting. Also, not sure how many work with the TT head protectors.
I have HnB bars which have the additional advantage of allowing the cylinder head rocker cover to be removed without dismounting the bars. Mine are black as I thought it would go better with the light gold cylinder heads and the forks. Very easy for one person to fit. But the spacers are different for each side so I did end up undoing at least one bolt to change the spacers over.