I haven't hiked with my Fenix yet, but I do have a Jakstrap http://www.liston.com/ecommerce/display.php?cat=3&zid=1&lid=1&nlst=&olimit=0&key1=&psku=
which works surprisingly well with my P2D/L1D. It's not all that secure with L0D (AAA) model (a looser fit), but fits the P2D/L1D body nicely.
There is a slight drawback to the asymetrical mounting, but nothing that can't fixed by futzing with the position of the strap (L-R and up-down). The glare from eyeglasses at night is a much bigger drawback since the light shines directly in the temple area of the lens.
The strap is a bit too wide (given the weight of the P2D with a Li batt.), but I've been eyeballing my old PT Scout's strap as a starting point for a retro-fit.