Yes, they are available.. The newer Loaders come with them.
NO, they will not feed as fast as a Halo-B, they will go 16-18bps, but the initial ball stack is not under load so the first 5-6 balls drop at only 10-12 bps.. so be carefull of chops at the start of a string.
The Halo-B on the other hand force feeds all of the balls, inc the ballstack, and is supposed to burst a lot more than 22bps.
PS.
Dark Warrior, how about reducing the size of your Sig mate.. it's a bit on the long size.