Two comm weapons become capable of outranging and rapidly killing Stingers with enough Advanced Targeting System upgrades: Heavy Particle Beam and Rocket Launcher.
Level 5 Engineer commander with 8x Advanced Targeting System, 1x Light Particle Beam, 1x Heavy Particle Beam
624 range. Outranges Stinger and all other basic turrets
Takes down a Stinger in 12 seconds (4 shots)
Outranges all skirmishers and one-shots most of them with 800 damage
Vulnerable to swarms
Moves at a crawl
Upgrade cost: 2330
Level 5 Guardian commander with 6x Advanced Targeting System, 2x Rocket Launcher, Napalm Warhead, free slot of choice
623 range. Outranges Stinger and all other basic turrets
Also takes down a Stinger in about 3-4 volleys
Keeps skirmishers away, but doesn't snipe them as effectively as the heavy particle beam due to rocket inaccuracy
At level 2 with only 1 Advanced Targeting System, already outranges lotuses and most skirmishers. Can get the last 2 Advanced Targeting System upgrades for 688 range.
More HP than the engineer commander, drones help give vision
Napalm warhead makes the rockets effective against swarms.
Can't aim upwards at too high an angle
Moves at a crawl
Upgrade cost: 2285 + cost of optional slot
So maybe it's a good idea on small maps to upgrade into one of these if you notice your opponent has really porced up with basic defenses and Stingers. Or if you're having trouble pushing back his skirmishers. Assuming he doesn't have anything that can easily kill a trollcomm.