I always find the man-portable RL to be a huge hassle in terms of inventory and TU management and plainly inferior to the autocanon in almost every situation. Autocannons can spam bursts of HE and incendiary shells nearly constantly, and even just one burst of AC-I or AC-HE is as good or better than a single rocket in every situation. And they can spam those auto bursts twice a round. Just two guys with AC-I rounds on a night mission can light the whole map up in 1-2 rounds.
I like taking along rocket tanks mainly because it puts the rocket launcher into the hands of someone who can't be mind controlled. It doesn't hurt that they're easily replaceable meat shields. And they never stop to reload. And you don't have to bring grenades or worry about arming/throwing anymore.
Optimum early game build for me is:
-everyone gets autocannons and stun rods, tries to stay alive and capture small launchers before snakemen show up, early research is all lasers all day long
-once laser pistols are done, makes some and ditch all but two of the AC carriers (who are mainly around for illumination purposes) and give everyone laser pistols (which are the best weapon in the game behind laser rifles)
-once small launchers are done, that's game. Capture or make stun bombs in massive quantities, give everyone laser pistols and small launchers
-once youve got a well stocked larder of live commander aliens, switch to laser rifles and begin the slow grind to world domination and flying psychic spess mahreens.