I have Halos and love them. That being said, the Alpha 1 is the exact same ski with a stiffer flex pattern and like you said, the race base.
I'd say base your decision off of your skiing: do you like to hit rails, do butters, presses, medium size jumps with the occasional groomer run? Halos. Or do you like to ski the whole mountain, prefer bigger jumps, and want the extra speed (and maintenance) the race base provides? Alphas.
Regardless of what you choose, both skis are very similar, and you really can't go wrong. I'd recommend the Halos just because they are the best skis I've ever owned.