Well, the Venture isn't going to get you the $100 off discount, because it's already less than $350. It's also a beginner board. So, throw that one out.
The Mauka is a big guy board that's very easy to ride and learn on. It carves nicely for a large board (probably due to the toed in fins) but it's a bit slow and requires a more weight up front to keep it in the pocket. This board will have a larger pocket and more speed than your Hyperlites, but it's a big easy riding board.
The Shaka is a step up from the Mauka with better speed and carving capabilities. It's also fairly decent on smaller wakes.
With that said, if you can afford it, I highly recommend the Ginsu. It rips. I actually like the performance better than an IS Sweet Spot. Pearling isn't in the Ginsu's vocabulary. And, it's pretty decent on smaller wakes, as long as you have some wakesurfing experience.
One word of caution with these 2010 Grindwater boards, however. If you're all about looks and finishes, look elsewhere. Your board will have surface imperfections, but it won't have any effect on the performance.
Oh, I've ridden all of these boards, so first hand experience here.