My thought/experience with using juices is that you are really diluting the flavors when adding it to fermenting wort or any other liquid. I would recommend testing this by adding small amounts to a lightly flavored beer, a wheat ale would be pretty ideal, and seeing how much you need to add to get a impression of the flavor you want. Now figure that this flavor impression will be diminished quite a bit through the fermentation process.
I tried using cranberry juice for a cranberry ale and did the above testing to see just how much I would need to add. Ended up with a double gravity beer which I then diluted with 50% cranberry juice. Still ended up with a beer where you had to know the cranberry was in there to sense it. Way too much conformation bias involved on my part as no one else was able to pick it out of the flavor profile without knowing it was in there.