Life gain on hit / life leech with pierce attack, does it work ?

Hello,

Maybe this question has been asked several times alrdy but i couldn't find an answer.
One friend told me that percing attack wasn't counting as a "hit" and thus life gain on hit wouldn't work correctly using pierce support skill or the node in the skill tree. he meant that pierced mob wouldn't proc life gain hit ....>.<

Is it true ? how does Life gain on hitwork exactly, what are the limits or special feature ?
Same about Pierce, it seems a very cool support skill, yet i don't see many people using which tend to prove it wouldn't work as well as it look like.

And what about life leech?

Thx for the answers!

Yes, life on hit and life leech work with pierce. The only things I can think of off the top of my head that dont work with pierce are:

-chain: will only chain if the projectile doesnt pierce
-fork: same as above
-explosive arrow: it will only leave a charge in the enemy if the arrow sticks (doesnt chain, fork, or pierce)
-Fireball area effect: it will only explode on the first enemy it hits. If it pierces and hits other enemies, it will damage them, but the area effect wont trigger again.