Reading MasterSeedy's posts, reminded me of something I meant to write. 'How likely are you to promote one of these non speed primary mods to ever know?'.
It could be that a non speed primary arrow will turn out god tier. However, unless it's already hit just the spot you wanted (double health for example) before, you're unlikely to 6 dot it, to ever find out.
So.........in the long run, speed's probably still going to be king; bar the few double protection/health/potency/tenacity mods you save, if you have the room.