I think what most people fail to understand, is that you have to use what works for you depending on your purpose and rifle setup.
Its funny when some guys make fun of those that use VFG's, or swear by AFG's only. Use what works for you depending on your application.
If you want a lightweight rifle with as little accesories hanging out, stick with your standard handguards with no grip whatsoever. If you need a VFG for sustained shooting, that put one on there. I've tried different configurations and they all work fine--its all about training. Personally I prefer Magpul's VFG, but also use their AFG. For me VFG works on my AR's because it helps when the rails/handguards get too hot during extended shooting.
Another observation is that I see many shooters that don't use VFG's in competition setting only. But why do you see the Military and LEO's use them?