I notice the dmg difference when I land crits on the skills. I'm currently subbing a tyrant and actually just started yesterday, didn't get much time on him, was in Cruma Tower, the difference between charging and not charging on a Hurricane Assault crit is about 1k dmg.
Hurricane Assault(lvl6) vs Catherok = 1500 dmg
Hurricane Assault(lvl6) vs Catherok = 1700 dmg (2 charges)
Hurricane Assault(lvl6) vs Catherok = 3000-3100 (crit no charges)
Hurricane Assault(lvl6) vs Catherok = 4200-4500 (crit with 2 charges)
Also note those figures are with Event Milk and Spirit Totem Ogre on. I honestly couldn't tell you why its only critting for 3k dmg even with those buffs it should be higher based on having increased crit dmg from ogre and the milk buff.
Sorry no SS atm, I'm at work, this thread popped up, I'm trolling on my lunch so I gave you the numbers i remembered..