I would not rely on SRM's even with infernos.
A Javelin? Hell no! PBI take a lot of shooting and there will be a lot of missing involved especially if they are smart and force you to play whack-a-mole with them.
You need a mixture of weapons including machine guns, small or medium lasers and any missiles will be for larger concentrations, opportunities and for taking out support weapons.
Vulcan and Flea are perfect for this.
Stinger and Locust almost perfect.
Firestarter and Phoenix Hawk are strong contenders.
After that anything else.
Vehicle SRMs have a greater range than Infantry do (barring Field Guns), and are far more reliable than most AI guns. Everything on the Burst-Fire weapons chart that you listed do random damage, averaging 7 PBI for a Machine Gun and 14 for the Flamer. An SRM-6 with Infernos will take out 18 PBI every single time. Cluster weapons don't use the Cluster Roll against PBI, after all. With the average Platoon clocking in at 28, with a custom 30 at the largest or 21 for the smallest preset, you've taking out more than half the Platoon and they are now either in, or close to, Forced Withdrawal.
Where the others have the advantage is mostly in weight. A Machine Gun is half a ton with a half ton or more needed for Ammo. A Flamer is a ton (with a ton more for Ammo if you opt for the Vehicle model). An SRM-6 is 4+ tons (3 for Weapon, 1 for Ammo). So for the weight of an SRM-6, you could be bringing 6 Machine Guns, or 4 Flamers. However, in order to use them you need to be in the PBI's optimum range.
Of course, if you can get them to hit, any Artillery-style weapon will do even better, whether it's a Piece, a Cannon, or a Mortar. AOE Damage does double damage to whatever they would do to a Vehicle, individual Battle Armor, or Mech.
Of course, that's in the open when they aren't in a Building. Getting them out of a Building IS hard, I won't deny that. Odds are you need to take out the building in order to kill the Infantry.
