I have an Arc AAA UV, and just received a white X1.
For a single AA cell light, the X1 ain't bad. The throw is not too far, but within it's range it is very usable. The X1 has a very focused and defined light disc. The one thing I do not like about it, is because the light is focused (appears to be focused by a lens), up close at a distance of a few inches, it is almost too bright. For example, if I was to use it for paperwork in a dark car, there would be a small, very bright, spot of light. The reflection would be uncomfortable to dark adjusted eyes - perhaps the red would be better for this. But, to find my way out of a dark room, it would be just fine.
To me, the Arc AAA is about the opposite. A nice wide flood for close range work, but not as much throw. The two lights are very much complementary.
I will also agree with the others here who have stated that the X1 is a bit too big and heavy for a keyring - especially car keys. I have seen ignition cylinders damaged from heavy, overloaded keyrings over time. The Arc AAA is better suited for keyring carry, the X1 needs a lanyard.