RE: Barrel length??
i dont like barrels that are longer than 7.5" . so id go with the 6.5" one. but that just the way they fir in my hand. also findind a holster can be problem for longer barrels if you dont want an accross the chest holster. i like my guns on the hip, but again its personally.
there is no great reason to choose one or the other. when it gets to a change of less than 2" then its all personal