Well if I could carry both I would.
Just tested if you could spot through smoke.
He stood on middle of hilltop, then I dropped smoke up there.
Spammed Q, and got the enemy is spotted message through the smoke.
That is fail, might stop using it now.
It still covers up your movements. I seen games change due to some well placed smoke. Not everybody is spamming Q. The idea is to go as a group of people. A few of you will slip by.