The guard doesn't cover the gas tube, which, if not protected, will be the weakest point of the rifle, especially if you're in a sustained firefight and it gets really hot and soft.

Handguard compatability? is it a drop in style that requires removing the delta ring and installing a barrel nut?

I let that count. The handguard is detached from the gas cap. It wouldn't stay in place rendering the handguard and attachments useless.

yeah it's too short and detached from the gas cap. 👇

That's not necessarily true. All of my AR-pattern rifles have a floating hand guard, and as such they are only attached at one end. A quad-rail attached in such a fashion would absolutely be sturdy enough to be used for all sorts of purposes like laser aiming modules and whatnot. So... The only thing "wrong" is exposing the gas tube. IMO.

No. It would work fine. Handguard are floating all the time. Attached at the back of the upper only. Actually how must nice rifles are set up. Ideally, it should cover the tube though.

This is correct. RAS is not a floating handguard.

Sure. The rendering needs to either move the FSB back to the handguard, or use the longer version of the handguard to hit the FSB.

100%