Unlike Jeff, I've been finding heavies to be the least useful of my crew. They're too slow to catch up to the action, their accuracy is too low to get the kills to level up, and I rarely bother using explosives. So I often won't take them on missions.
But man, oh man the guided fusion launcher has suddenly made the heavy one of my favorites. Anyone else got the heat seeking rocket replacement?
My first time trying it, I was inside a store, when a cyberdisk and drones appeared outside of the store. I decided to blow up the wall and therefore give my other soldiers line of sight. Instead it shot out, turned left and exited out the back door, swerved around the corner and then obliterated the cyberdisk in one shot. In one move, it accomplished what would have taken me at least 3. This changes everything.
Anyone else using this thing? It seems most players miss it (I've heard many forum posters claim there is no rocket launcher replacement, not true).
It is a little hidden since you can only find the research item needed by invading a battleship-class UFO, but boy is it worth it.