I switched from surefires to modlites on my business-time guns in the past year. The output is bananas and 18650's and 18350's are so much better than an endless stream of CR123s (Although I still have an endless demand for CR123s).
I think the PLH are prob the most useful, but the OKW's are outstanding for throw. I got one of the PLH V2 heads yesterday and it seems to be the best of both worlds. These simply do not compare to the Surefire Scout's in terms of downrange output.
Incidentally, I have started carrying a OKW handheld in my pack hikes in the mountains. In the past years I have run into situations at night where my headlight (450 lumen petzl) and my EDC handheld (surefire tactician) are woefully under powered to identify trailmarks (especially above the tree line). The OKW is an absolute beast and has a throw that projects over 100's of yards and can punch through enviromental barriers like snow, rain, fog.
It might not be useful for everyone, but for the role it plays, it is spectacular.