Here is where I entail my personal experience with the G402 Hyperion Fury. Off the bat, the mouse is great. Now let's see why.
The sensor, though it's an AM010 variant, which had some severe issues on the G100S, behaves a lot better here. There is some slight jitter to speak of, especially on SteelSeries' QCK Heavy, but the amount is negligible.
What about acceleration and prediction? I feel most manufacturers have wizened up to prediction, so you won't really find it enabled by default anymore. Acceleration, on the other hand, there seems to be some positive accel, I won't deny it, but it's consistent throughout, and it's again, negligible.
There was an important issue with G100S' AM010 sensor implementation; it lost tracking at around 150ips. I imagine those limitations are still in there, which is why it's so impressive what the accelerometer / gyrometer do to the tracking. For a low-sensitivity user, 150-200ips is the average, and peaks are around the 250-300ips mark. Hyperion Fury handles this tracking with ease, registering movement at speeds that are almost double.
Lift off distance
Since there's no lift-off distance customization, I think I should weigh in on this too. It seems the lift-off is very low, between 3 to 4mm, or in common term 1 to 1.5CDs.
Hard to define the shape of this mouse. Unlike its older brother the G502, G402 is actually slimmer, with a lower profile, and redesigned button position. From what I can tell these changes were done to acommodate the claw-grip user as much as the palm-grip one. You get much better access to the side buttons, and the overall feel is considerably better for claw-grip.
G402 is a lightweight mouse, even though it's quite large. It's designed to appeal to shooter-enthusiast folk, specifically, the low-sensitivity ones. The accelerometer implementation is great through and through, even though there's some slight positive accel, it's consistent, which means you won't get erratic tracking at any point.
There are only a handful of buttons, and a more spartan build, even the quality is not on par to the G502.