Smoke still give a bit of stun damage, but only once by turn. The funkyfire bug made hit suffocate people additionally every time a fire bullet explodes anywhere.
Yep, you could stun whole batches of aliens, at least, until you ran out of smoke tiles.
Honestly, the incendiary rounds should do some more damage over being on fire. Being on fire and being covered in napalm, or more likely: thermite / white phosphorus are very different things.
Maybe something to play around with when I get my code base standing up.