Author here, yes it very much usable but its also very much in a raw shape, i.e. its only for a hunter, and you need to have both wing clip and autoshot on youre bar for it to even work. It basically uses those 2 abilites to check the if youre inrange, outofrange or in youre deadzone.
Ill clean it up for tbc after im done with BigTrouble.
I use Nudge since I got rid of most of my buttons I previsouly used for range checking. It's easy to change to work for other spells and I changed it to show Mind Blast as I play a priest.
I also made a separate version -- NudgeNudge -- which is the same code hacked to work for friendly targets and specifically for Dwarven Priests by showing OOR -> Healing -> Fear Ward. This is very useful on Nefarian and Magdamar.
So if you do develop it further this functionality in a snigle add-on would be great.