Just to pipe in with some accurate Jackson information...
The ZG and the FUN series of boats are COMPLETELY different boats with completely different designs. The "AllStar" series of boats is the Jackson you really want to compare the ZG too and unfortunately no one in Colorado has been in one yet, but most retailers should have them in 3-4 weeks. We just pulled the very first AllStar out of the mold on Wednesday and I used it yesterday on the Upper Ocoee. I am not that great of a playboater but even so WOW!!! Better get your freak on if you want to stay in front of that thing!!! but that is for another post.
The Fun is a completely different boat and although it's been proven to do basically every trick that is currently out there, it 's a river runner first with tons of stability and a big focus on comfy/light with the ability to do some pretty impressive surfing/play.
Jed and Brad are correct... the Fun is really stable on any class of water, I understand it's being used a bunch in Gore lately and although I haven't been in that big of water with it yet...it is being hailed quite positively. But if you are looking for a truely "Apple to Apples comparison" type of boat to the ZG (i.e. freestyle boat) you will have step into the "Star" series of Jackson boats.
Feel free to send me an email if you have any questions... I should have one for my demo fleet in the next couple weeks.