8 speed chains aren't going to be as light because they're wider than 9 or 10 speed chains.
Also SRAM doesn't really make them with performance in mind because they probably assume that if you were a performance oriented cyclist that you would have a 10 speed group.
the chains are Beefy! bust that sucker out, and ride your 8spd like it's hawt... Honestly I would ride at 8spd still if there were better choices than 2200/2300