Have thought about it and here's what I found out:
It sounds good on paper but is touch and go in reality. As a rule, the gas tube heats up during firing and that is bound to cause some movement. One CGN'er bought an aftermarket gas tube scope mount and installed it in real tight but still had issues as the tube heated up. It may work at times but one thing is certain: It wont' 100% of the time.
So if you go that way, the only issue is that you will always have that nagging thought in the back of you mind whenever your POI begins to wander.