I use both depending on the size of the gun. My XP100, and Striker are just to big for a holster, so I sling them. I use a holster with several Contenders and my Blackhawk. A neighbor just got a nifty holster for his scoped 15" Encore from Fox Ridge, the Thompson/Center Custom Shop (on the web). It's a bandolier style (slings over one shoulder)that hangs from his left shoulder on his right chest (he's a lefty), the back of the holster is open to accomodate the scope.
Looks relatively trim and yet comfortably carries the big piece.