let me clerifi. I have the smartparts halo that comes with the metal bearings, and I'm not shore why but they say it's lighter then the standard halo, and It is quieter then the reg halo (or so I'm told).
The halo ma look bigger sitting on your gun but thats just because of the shape. When you put it side by side with the rev is nearly the same size. it just looks bulky because most of the mass is at the rear of the loader, so when you look from the back of the gun it apperes to be bigger BUT IT'S NOT!
As for price it is a little expencive, but hay so are all of the guns that can out run the rev, did that stop you from buying them. No.