1. Flaq HQ allows you to create a safe zone where the ISG can fire without worry of being harrassed as well as the medic HQ where they can be reinforced if counterbarraged.
All you said is correct but this could have a downside too, and an important one. A few dayhs ago I have played a 2v2 as USF against OKW+wehr. And the OKW guy did just what you said. I called a priest. Just one, I didn't need more. Not only I constantly killed its crewed and recrewed ISGs, (and with walking barrage too ) but because the FRP was at his med truck and of course the ISGs where close, I scored 2 hits on ISGs AND his retreating blob.
So, I don't know, it has counterplay, and a strong one may I say.
2. Longer range makes them harder to reach and harder to fight with indirect units.
Agree. It is good.
3. Gun sheild allows it some protection if it comes under fire (no such luck for the pack)
Yes, it's true, but I don't think that places it over pack howie in overall efficiency and worthiness.
4. Especially strong vs. the brits who have a more static playstyle while lacking decent tools to counter it.
IT IS strong against anything that looks like infantry or emplacement, but shouldn't it be?