So is it safe to assume that the HB2 (9003) puts out more light than the H4?
No, it does not.
And, that the GE Nighthawk Platinum is the better choice in that bulb?
Better than what? The GE Night Hawk Platinum is a very good bulb, but the Philips Xtreme Vision is better, and there are others that may be even better still, depending on your specific application.