Take a Pioneer squad and Combat Engineer squad. As they are, they fill almost identical roles, with the Engineers being slightly less cost-efficient in terms of DPS while having additional synergy with M3s. So instead of granting them nearly identical veterancy bonuses past the vet 1 ability, why not differentiate?
For example, the Pioneers could fill a more support-oriented role with veterancy like this, capable of keeping the heavy Ostheer panzers up and running quickly while actually making the field first aid ability cost-effective:
Vet 1:
- Field First Aid
- x0.8 received damage
Vet 2:
- x1.5 repair rate
- Mine-laying cost -5 munitions
- Field First Aid cost -5 munitions
Vet 3:
- x1.5 repair rate
- Mine-laying cost -10 munitions
- Field First Aid cost -5 munitions
- No received-damage penalty for repairing under fire
While Combat engineers could live up to their name with veterancy that augments their direct combat capability:
Vet 1:
- Trip-Wire Flares
- x0.8 received damage
Vet 2:
- x1.2 Movement speed
- Weapon upgrade cost -10 munitions
- x0.9 received damage
Vet 3:
- x1.2 accuracy
- x0.9 received damage
Different infantry types could have different veterancy types. For example, Panzergrenadiers, Shock Troops, and Penals are entirely combat-oriented, hence could have more movement speed/accuracy/damage resistance bonuses. Regular line infantry like the Grenadiers, Conscripts, and (to an extent) Guards could mix ability-cost discounts with combat and line-of-sight buffs.
While these statistics are just examples (and may not be balanced) and such a significant change is unlikely to be implemented at this stage of the game, it's still an idea I think would significantly add to the depth of the game.
Thoughts?