^^^I started something similar to this on March 3, 2011, with some mangos I threw in the blender.
My plan was to use the C-ville Kevin method with ale yeast and cold crashing to produce something semi-sweet. This has worked VERY WELL for me with store bought apple juice. I planned to stop it somewhere between 1025 and 1008 specific gravity.
However, on my mango concoction, I accidentally let it ferment out bone dry. So, I just left it in the fermenter (after several rackings along the way to get it off the fairly large mass of pulp debris). Five days ago, I racked it again and tasted a tiny bit. It did not taste great. I don't really know how to describe the taste....there weren't any really strong distinguishing flavors or anything. It just wasn't great.
I'm sure people have done something similar with much greater success. Maybe you could just catch it before all the sugar is fermented out, and it would taste great. But, if I was looking for a more foolproof method, I would probably go with the mango pulp wine. It looks like people are having really good luck with that.