The best way to alternate pick is with the heaviest possible pick. This is what I've observed from my own experience and from watching other incredibly fast guitarists. The heavier the pick, the more 'attack' it has, and subsequently, the less effort required. Those special picks that are flexible in the middle (like Dava Control) are just novelty and will only get you into bad picking habits, especially if you go back and forth between pick brands and types.

What I'm learning right now? How to procrastinate late at night before a f'n final exam at 8 am. :(