Yesterday i try the Missile launcher of the Heavy Weapons Specialist Class and the Supports Class Detpack against a Tank:

Missile launcher: 7 Hits to kill a Tank, 3 Hits against a Speeder, 1 Hit against a Speederbike.
Detpack: 4 Packs to kill a tank.

Even a Full Squad of Heavys with Missiles won't kill a Tank if every Squad member hits, and i did not notice a sweet spot on the tank (a point there the missile does more damage).
And with only their Pistols they are helpless against Inf

Two Supporters can kill a tank quickly, and with with   their Mines and Blasters they can stand good against Inf.

IMHO this is Bad, the same problem like the SpecOp in BF2 Vanilla:
The support is better equipped to take out enemy vehicles than the Heavy with missile Launcher.
He is better equipped to take out Inf than the Assault, because his weapon has Burst mode and Zoom and he has mines. He is even not limited by ammunition, because they can resupply him self.

I am not feeling comfortable by suggest a redesign of the classes (because you have a done a lot of testing and there is surely a reason behind your class layout), but:

Heavy Weapons Specialist class:
Enlarge the ammount of damage for the Heavys Misslelauchner against tanks
Change the Portable Shield Generator against the Proximity Mine
Remove the Electrostatic Charge Detonator

Reasons:
The Shield Generator is cool, but it also marks your position clearly for each vehicle.
The Promixity Mines will help this class to defend a stronghold against Infantery.
Both changes will make this class a better defender.

Support Class:
Change the Detpackspacks against the Homing Beacon of the assault.
Change the Proximity Mines against the Portable Shield Generator
Give him the Electrostatic Charge Detonator

Reasons:
With the Shield Generator and the Generator this class can build save resupply places. Behind the front, or at the front. With the Homing Beacons he secure this places against a enemy attack.
Without DetPacks and Promixity Mines he can't spam them.
With the Electrostatic Charge Detonator he has still a weapon against enemy tanks.

Assault Class:
Give the Assault Rifle a Burst Mod.
Change the Homing Beacon against the Detpackspacks of the Support.

Reasons:
With Homing Beacon, inaccurate Weapon in Full Auto and no Chance against vehicle this class is not suited for an daring assault.
This class is more suited to camp behind the Homing beacon, waiting for the enemy.
Burst Mode will make the weapon more accurate during moving, removing the Beacon works against camping and the DetPack gives him a small change to damage a vehicle with a brave attack.

CYNIC, n. A blackguard whose faulty vision sees things as they are, not as they ought to be. Hence the custom among the Scythians of plucking out a cynic’s eyes to improve his vision