Hey Elixir, I'm thinking of picking up an Onza. What's your opinion on it? I'm thinking of siwtching to it to get the two extra macro buttons for use in Battlefield 3 but I'm wondering if the better D-pad and adjustable thumbsticks are good for STGs. I've always had trouble deciding whether I liked pad or arcade sticks better.
Absolutely not. The dpad and well, the entire controller, were made for console FPS in mind.

The Onza's dpad is not really even a dpad, because it's made up of buttons. It's done so you can choose weapons in FPS. I couldn't fluidly use this like a Saturn pad (which I'm almost always using as it's my preferred controller), and I gave up almost immediately trying to play Castlevania HD, Bomberman, and any shmups with this. Dpad itself is a total write-off.
Analogues are nice, you can twist them making them loose or tighten them (in notches) to make them stiffer. Buttons are mechanical, but I felt like they were too close to the controller, lacking depth. If they were perhaps as large as the regular 360 controller's buttons, then sure. But they're not, they're much smaller and much lower to the case of the controller. I also had an issue with the triggers, because they're "pointy" and curve at an abrupt angle, unlike the 360 controller which only has a small concave curve.
The newer Slim 360 controllers actually have a much better dpad, but years of people claiming the 360's dpad being awful seem to overlook this fact. In fact, I would go as far as to say that the bundled Slim 360 controllers are better than the Onza.
On the bright side, the controller had a nice matte finish and the adjustable analogue sticks were useful in 3D retail releases, like Bayonetta. I can't really recommend the Onza though, I ended up selling mine.