The light you mention is very interesting and many times with light, more is better.
One of the ads I saw for the Archon advertises light coming out the side of the front lens, as if that is preferable. However, light coming out the sides may increase backscatter or just a glare in a diver's eye. I do not know that, but I do know from years of teaching and shooting u/w photography, that you do not want to light up the area between your subject and the lens, which a side light will do.
The Archon only comes with one battery; a second battery is another $25. The UK light comes with 2 batteries that can be charged from a laptop; the Archon may charge from a laptop, but I did not see that feature advertised.
The Archon does not come with any way to mount it, so a bracket must be purchased. The UK light comes with (2) 1/4-20 threaded holes that makes mounting easier, but one still might have to purchase a ball joint to mount.
I also noticed the size of the Archon, which is almost twice the diameter, longer and heavier.
Please, I am not putting down the Archon light! I would love to have 1400 lumens; that does remind me that the UK light has 4 power settings, but the Archon only has two.
I think you could not go wrong on either light. If you get the Archon, let us know how it performed; one post and video I saw showed flickering with the Archon light in low power mode. Not sure why that happened, but that could be a deal breaker for me.