I have been searching for the most effective strobe light for a long time. I have purchased every single Quark 2*CR123 'Tactical' light ever made. I have settled on this one mainly because you can program the light into two modes (one with tight head, the other with loose head). If I'm going out for the evening, I tighten the head and it is in strobe mode (my setting). This means there is one big button in the back, and if I press it, the light will strobe. There is no fumbling trying to hit a second button, or a side button, or two presses, etc. Under any sort of duress, one simple button press will be a big advantage.
Currently I'm carrying the QT2L-X with 2 RCR123's, and it strobes in 'burst' mode, which is advertised at 780 lumens with standard CR123's, probably a little higher with my RCR's. I just wish it strobed at a rate similar to my earlier versions (R5 or XP-G2).
This light is relatively small, which is another big advantage over the competition.
I am hoping to see something hit the market that resembles the "Dazzler" that the military is developing.