Shock troops have about 14% better EHP and DPS on close range, they are a decent bit better in raw combat. Assault grenadiers have (my opinion) the better nade though and also bleed you a tiny bit less.
And on a small side note: Some weapons like HMGs and LMGs have increased penetration. Depending on your opponent, the Shock troop armor is worth less than calculated in a "standard" formula.
Yeah, but with LMGs you generally fight shocks at far range with pen of 1, which is the same as other small arms. HMGs on the other hand care a little bit more that none at all about their armor, especially hmg42.