I change my spec every 2 weeks or so. Right now I'm playing around with strikethrough in a melee spec. (92% ST) I've gone the full up ranged for the same reason that Arica posted. I've tried full up melee and it's higher dps for me. The trick is just remembering to switch to auto ranged on harder fights when you can't get in for melee ranged reasonably.
So for me, at least, melee = higher dps on easy fights, less dps on harder fights. ranged auto = mediocre dps on all fights and less worry about positioning.