I’ve no idea how bright a diablo mk3 is but i recently took a chance on a chinese headlight for less that a tenner.
its good and bad
the good
its brighter than my alpkit gamma.
takes 3xaaa
its light
its cheap
the bad
the build quality is poor
the battery compartment is barely sealed with a rubber cover and not in anyway water resistant
the light angle is adjustable but not in the right place but can be fixed diy style
the zoom is stiff and useless
battery life unknown but suspect it will be enough for must runs
conclusion, it does the job of allowing me to run at night without breaking the bank, i think one modified for waist use with this on your head would be a great combo
i think a backup torch would be a good idea as reliability is unknown