I agree with Plato that you would be better off with the 9" arm and the TT improvements. The TT/motor assembly is higher on the analog hierarchy scale, and will make more difference than the longer arm will.
The only differences that the longer arm makes is an extremely slight reduction in tracking error, and slightly higher mass that may be a better match with certain cartridges.
The only differences that the longer arm makes is an extremely slight reduction in tracking error, and slightly higher mass that may be a better match with certain cartridges.