I did a 15 mile ride tonight with my DiNotte 200L on the bars and my Fenix LD2 Premium Q5 on my helmet. It is exactly as the OP says in his section "DiNotte and Fenix together." This combination worked beautifully!

I mounted my Fenix to my helmet using two reflector mounts: a large one (seatpost reflector bracket) goes around a vent hole in my helmet, thus giving my Fenix vertical adjustability; a small one (chainstay reflector bracket) goes around the Fenix giving me horizontal adjustability; the two screw together in the middle. This mount was free, made from spare parts I had laying around, and works perfectly!