I decided to switch to a Halo B from a VLocity because I would rather save the extra cash for a different upgrade to my setup. I'll never need to shoot that fast. The rip drive is incredibly handy to have, just like everyone has commented before. It's easy to feed a few balls and chrono or test fire.
The Good :
As I stated above, the rip drive is so convenient. The weight distribution of the hopper is also very nice. The batteries sit in the front, so you have a better balance over your hand on the grip. The feedneck is nice and thick, so you can tighten down onto it with your clamping feedneck easily. My friend couldnt tighten his gravity hopper because balls would get stuck feeding through the clamp.
The not so good :
It's a heavy hopper. 6AA's does have a lot of weight, but contains more mA than 2 9V's, hence longer lasting. You get used to the weight though. Battery replacement requires a screwdriver and quite a bit of prodding to align the cover correctly to close. The on/off button is manageable, but would be easier if it were a toggle switch. The push button switch takes a couple of tries to work.
The Extra :
So far, I have put about 2 cases of paint through this hopper and have yet to replace the batteries. If you are going to use alkaline batteries, use name brand batteries. There's a reason why those other batteries are so cheap. I'm sure that I'll need to replace them soon, so always have an extra set of batteries handy.
Overall, I love this hopper. Price could be better, but so far, it has performed up to its value. I'll probably keep this hopper until the prices on hoppers start to fall. Then, maybe I'll migrate to a newer hopper. This will probably last me well for the next couple of years.