Some good points. But people tend to three bet light. That being said, you can't automatically dismiss 67, any 6X, or 77. Those are the exactly the type of hands with good implied odds
because they are unlikely to hit most three bet ranges. Im not really a fan of your 6X open either. That opens yourself up to a 20 BB reraise. And most times on the flop, you'll have no idea where you are at. So opening that hard, you're forcing yourself to fold to a possible 20 Bb raise or call and be guessing. I like neither option. There is an old saying. Big money is for big hands. This isn't one. Better to call it a loss and look for better spots.