For sure lighter wheels will reduce the unsprung weight, helping handling, ride etc.
But are the GTA wheels suitable for the basic v6, i.e. how would the offset affect the handling and straightline stability? Was reading an earlier post recently with some tecchie stuff (relating to the offset radius or somesuch) discussing this.
Would be interesting to drive a car with the 17" GTAs and the 17" Selespeeds back to back and compare.