Well i own a "Halo A" you could say, theres two, the Halo A and the Halo B, the difference between the two is that the Halo B has a "better drive chain" wich lets it cycle faster, quieter and with less power.
The Halo series uses two power sources, you can either use 6 AA batterys, and with the Halo A get 15 bps, and with the Halo B 20 bps, or you can use a single 9v battery and you will get 10 bps with the Halo A, and 15 with the Halo B (this is aprox according to a number of speed tests i did with 150 balls, a Halo A, and a stop watch.
The Halo holds 150 balls VERY nicelly, and will hold up to about 170, its just about the same size as a revvy but weighs about twice as much, probly becuse of the way it works wich ill get to in a moment, and that fact that if you want the best BPS out of it youll want to use 6 AA batterys wich are "Fairly" heavy.
The way the Halo works is you have a normal hopper/loader but instead of having a paddle(s) that spins or pole that shakes you have a "lazy susan" if you will, for those who dont know what a lazy susan is its a plastic circular device that has slots in it to put things in, and it spins around on its base, anyways i like to call it a turn table sence it sounds nice and is simple, what happens is the balls fall to the bottom of the hopper and there are holes in this "turn table" that the balls fall in, this turn table spins around and when it gets to the feed neck the ball falls down, now this is a very interesting desgin and im sure i could have explained it better but i did the best i could.
Lets see..the Halo A runs at about $100, you can get one "cheap" at www.paintballgear.com
and also you can goto www.google.com
and type in odyssey halo loader and itll come up with a bunch of websites that are selling it, or you can just go directly to http://www.odysseypaintball.com/
wich is the official page (its also the only place i know of that you can buy the Halo B, usually you buy the Halo A and then you have to send it to odyssey and theyll "upgrade" it to the Halo B for $30.00.
All in all if you have the urge to dump paint like a mad man (back players of the sort or people who just like to rip off 20 bps at someone and watch them run for there lives) then this is what youve been waiting for, if your a front / mid player and you dont mind the added weight then you shouldent have much trouble with it, on the other hand if you must have a light gun then this probly isnt the loader for you.
Ide give the Halo A and B a 9/10 ide give it a 10 but they need to find a way to lighten the load.