I voted for the mag with a warp feed. They are incredbile with warp feeds.
If you go to www.webdogradio.us
and look at some of Tygers FPS series, hes using a warp feed mag. He plays alot of woodsball and prefers it over speedball and such... The nice thing about the mag, its pretty much limitless... you can use it for both speedball and woodsball comfortably without feeling limited by its abilities.
Otherwise I would go with one of these autocockers:
Those were the origonal AC woodsball guns.