User blog comment:James12708/Reapers VS. Forerunners VS. Angels from Darksiders VS. Humanity from Halo VS. Council and humanity from Mass Effect VS. Imperium of Man/@comment-4721065-20130112104250/@comment-4721065-20130117064206

Yep, they can... if they divert all power to their anti-gravity at the expense of shields and guns. They usually only fly at the height of three metres (meaning that they would be in melee range even for regular Orks) and even then, they cannot fire their beam and keep up the shield at the same time, having to choose between one or the other. In short, if some of them do accelerate fast enough to get out of Stormboyz' range, they wouldn't have enough power left to do anything meaningful. (And that is before you consider the fact that Onyx Sentinels MIGHT NOT BE present anywhere BUT on Onyx, and that regular ones are much weaker.)

As for the second part, I would appreciate some quotes if possible, but even if all that is true, that still doesn't prove them to be superior to Orks' most powerful tech, as there is far too much detail missing. I also think it's worth remembering that visibility of the explosion doesn't have to be directly linked to its power: gasoline is one of the weakest modern explosives, yet it is just about the only one producing pretty cinematic fireballs instead of some gray smoke like what you get from C4.