I realize that it has been 1.5 years since somebody posted to this thread, but I was just doing some random searching for this flavor and this came up on Google.

I was a taste-tester for the product. It was at-home tasting, and I still have six sealed cans of it, non-diet flavor. It tasted quite good. It was disappointing it never came out.

Not long before that I taste-tested a new Mountain Dew flavor that was never released. It was an electric blue-green color, a melon/passion fruit mix. I have two 20oz. bottles of it still, and unlike the Sierra Mist Mojito, that came all labeled with package design.