I don't think there has ever been a Legendary shoot to loot weapon before. If there has been, it's probably pretty rare. This will be the first weapon I buy when HoW is released! You can see the sniper, and it's perks in DPJ's video: http://youtu.be/1EPMZkv8RCA
The sniper is around the 3:46 mark.
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I don't think it'd be too good to have a sniper waste a perk slot on a utility perk. Probably better to just stick with a green/blue shoot to loot scout. If you have to use shoot to loot, you're probably pinned behind some cover so chances are you'll have the opportunity to easily swap weapons.