I work with my hands. Mloc, keymod and/or picatinny are plenty comfortable to my mitts.
Airflow is good if you can afford mag dumps. If it’s a working rifle, airflow won’t be an issue until you take it to war. Basically, if you’re in the habit of shooting your barrel hot, I suggest concerning yourself with airflow.
Most of mine are covered. After 100 rounds over the course of an hour, didnt notice any absurd overheating. Agree with @dred probably only an issue in combat.
theres lots of other things on the sub bound to fail ahead of a melted foregrip, under those conditions.