I think the pendulum swings both ways in the first hour...And, perhaps, that is the reason the volatility is greatest in the first hour...I find the best opens, as far as potential to exploit, occur the further you open from the previous close(either up or down)...The unchanged opens from the previous closes typically are the most dangerous as it takes alot of chop in the first 15-30 minutes to create enough of a bias one way or the other prior to the "thrust" which occurs sometime between 10-10:30(ET)...
Either way, it can be very dangerous to trade the opens if u are not prepared...The whimsical trades in the first 15-30 minutes, oftentimes, will not give you a good margin for error if you are not committed to that trade...Likewise, if you catch it right, especially positioned on the right side prior to a gap fill or an economic number you can get a quick sudden move away from your entry, and many times the Swing High(Swing Low) will be made off of that price bar...