I love voulgiers personally, and if the french had musketeers I probably use them more though. Must make do with aventuriers...
Keep the spearwall and guard mode on, and after the enemy charges the wall turn off guard mode immediately and set them hacking. Spearwall doesn't seem to make that much of a difference, as they have no secondary weapons and they don't poke anyways. But its good to have a non-spear infantry that can survive a charge and have AP.