I would not call it a prototype, it is not like the other versions they have made, but not a prototype.
..matt
Just hop on over to Screamscape and take a look at the picture for PGA's rumored new ride. Its an extended version of Zamperla's Disk'o attraction. Just throw in a bunny hop in the middle. Quite honestly, I dont' even consider it a coaster. Having ridden the Disko up at Mt. Olympus this summer, I was very underwhelmed. I thought the restraints weren't the most comfortable and the ride surprisingly made me a bit on the sick side.
On the issue of Mack, though, I'm VERY curious to see where that ride lands. If I remember correctly, Thunder Run up at Canada's Wonderland was a Mack powered coaster.....it was a ton of fun!