Finally got my new head today, most noticeable difference is the longer contact spring. So as usual did a wash down of the light with new head installed, for some reason before fully submerging it (standard personal water proof test) I took a look inside the reflector and there was water in it. Immediately took it out and dried it. Glass was fogging up already.
So yeah, learned how to open the head, tape on head and body, lay it real thick and nice then use hand powwah!...Left light on turbo to dry out the inner parts with the reflector off.
I tried seating the O-ring in front of the glass, however when I tighten the head the oring gets forced out as there is no groove holding the O-ring under pressure, just a flat shelf.
In the end I just applied some superlube to the lens shelf, oring and the portion of the reflector where the o-ring sits on. Seems pretty watertight for now but I do not recommend submerging for prolonged periods.
Despite above issues, this is still my favourite EDC currently and my brightest single cell light so far. Needless to say it gets the ooohs and ahhhs from the uninitiated around here