I'm not sure what the point in pitting Penals against Sections is given those factions never face each other, but I ran some tests on Rifles versus Grens.
In a 30 range full cover shootout with the base squad, the score was 4:4 Grens:Riflemen.
In a 30 range full cover shootout with one weapon upgrade (LMG42 vs BAR) the score was 8:0 Grens:Riflemen.
In a 30 range full cover shootout with equal models (4 Riflemen vs 4 Grenadiers) the score was 8:0 Grens:Riflemen.
That suggests to me that Grenadiers are carry infantry like Panzerfusiliers: they're really not that good early on. However, once they get their weapon upgrades and veterancy they punch above their weight at their preferred ranges.
What is the point in this.