I just took a gladius on loan from my cousin and will post some beamshots up once i get the chance to take some.
others who have had both the U2 and Gladius together will be able to post better long-term impressions, but my initial take (and this is really nothing new from what has already been said) is that the U2 is definitely more floody and puts out more light in that flood pattern. operation of the U2 is very simple/basic, you turn it on/off with the tailcap button, and you adjust levels with the ring. while you can operate the U2 with one hand, it takes some doing. however, having the ring means you can jump to any of the 6 levels pretty quickly. pretty much that's it for the U2. it's bright, and it's simple to use and operate.
the gladius is not as bright overall as the U2, but beam is more focused and throws much better. keep in mind the U2 is not that bad in the throw department, coming close to the lux rating of the A2 as per Quickbeam's review. however, the gladius definitely outdoes my U2 on the throw bit.
spillbeam is dimmer, yet it is still bright enough to see what you need. i'm not a LEO type, but this might be more useful, as the concentrated beam would be more effective in the face of some perp, while the spillbeam is bright enough as to see by yet not so bright as to compromise your own night vision.
multiple levels is far easier to operate one handed than the U2 - go to constant on mode, and hold down the button to cycle up or down the levels, and you get an amazing number of levels on the gladius. however, jumping say from mid-dim to mid-bright is harder, because it has to step through the levels first.
and the strobe. what can i say. i thought i had it pretty decent with the Flupic strobe on my JIL Intelli. but the gladius's strobe is truly far more disconcerting than anything my JIL throws out. this isn't a knock on the flupic, it's a great light and does its stuff very well, and you can adjust the strobe. but the gladius does it far better, and i can get myself nauseous by even strobing it at a shaded area in a lighted room and staring at it. i have since tried to calibrate my JIL's strobe to the Gladius's, but haven't got it quite right.. i don't know but it seems the gladius might have a variable strobe effect, slowing down & speeding up while you hold it down. suffice to say, i wouldn't want to be on the other end of the gladius strobe.
as far as a video of the gladius strobe goes, i don't know how effective that would be, that'd depend on the frames per second capability of the camera, and the subsequent encoding of the mpeg/avi/mov/whatever file. as far as the tailcap goes, i read about it but completely forgot about the nub alignment, etc. but intuitively got it at first go when i got the gladius, so it's a non-issue for me. but i think this gladius was of the batch with the tailcap problem where you might have to take it off to reset it. but this problem has been resolved already, so if you get a new one, it's a non-issue, if you have one of the problem units, send the tailcap in and they will fix it for you.