The Alpha is stiffer than the Halo, so it really depends on what your skiing and the size/nature of the features your hitting. Personally if I skied more jumps and the jumps I hit were larger sized features, I'd take the Alpha. But if I was skiing mainly rails, and just hitting small jibs, I'd choose the Halo.
Both will be very good for jibbing, it just depends on if want the faster base and stiffness. If you're more into presses, butters and the like go with the halo's. If you like going fast and doing more rapid spins off bigger rails/jumps go Alpha. Both can still do everything but each one has their own strengths.
it ain't Saturday, but it don't matter to me... GOT NO JOB!
dont wanna make my own thread but i am kinda in the same situation but i would get this years because i want a 80 ish underfoot park ski, im 5'8 140 and really growing and expecting to grow alot more, i like going fast and going big but also jibbing around, i spin 40 ft jumps and straight air bigger ones and hitting rails and shit. also looking for the ski to be playful. also looking at ar7, thall, and punx