Something that really bugged me out is the fact that with a heavy carrier, you only have 2 rounds for your grenade launcher and 1 with a light carrier. Two is, I think, really not enough and realistically, you would carry more. I Think 5 rounds with a heavy carrier should do the trick and 3 or 2 with a light carrier is a good compromise.
Grenade launchers
In first insurgency you could carry five if I'm not wrong and that was op, good thing very few people did it