I've used 100% raspberry jam to good effect in a stout before, it has a more "cooked" fruit flavor that I like in darker beers. If you want mango flavor I would use something that has mango higher than the 4th ingredient:
■Ingredients: Peach, Sugar, Dextrose, Mango Puree, Glucose Syrup, Fruit Pectin, Citric Acid. Fruit Content: 52%.
I really enjoyed the Cigar City mango IPA, which apparently was “Cask conditioned on dry hops, mango acai tea, and a hint of lavender.” Which i have to suspect is: http://www.celestialseasonings.com/products/detail.html/herbal-teas/acai-mango-zinger