Chronometer works pretty well UNTIL you have an ability with a multi-spell macro that's a part of its use. Then it falls flat for me.
Example. As a druid I might have a simple attack macro for early levels made up of this.
/script if not IsCurrentAction(48) then AttackTarget();end
/cast Moonfire
If I use this, it puts me into auto attack mode after checking and finding that I'm not in it (my attack button is placed on my 2nd right hand ability bar, last slot) and also casts Moonfire. The Moonfire duration WILL show up with Chronometer as there's nothing confusing it.
Now if I use the following complicated macro as a different example of two abilities capable within the same macro text...
/script if buffed('prowl') then CastSpellByName('pounce') else CastSpellByName('faerie fire (feral)()');end
What happens here is that if I am buffed with Prowl (stealthed), I'll cast my Pounce opener. And at all other times that I do not have prowl running, I will cast feral faerie fire instead. When I cast faerie fire on a target with this, the duration will not show up with chronometer because it becomes confused for some stupid reason as the source macro had more than one ability listed within it.
A small work around you can try is if you are using NatureEnemyCastbar addon. There's options for different effects sourced by your character being tracked by the castbar addon. For rogues using macros with Gouge, it's pretty darned handy.