I have the WeatherTech deflector. It works well and I've had no increase in noise. It is attached via heavy duty double sided tape which has held up well for 2 years and 40,000 miles. The rubbers stops for the hood also hold it in place when closed.
The GM OEM deflectors were mounted via tabs and rivets/screws and the tabs tended to break off. Admittedly, I do most of the maintenance on the Outlook myself so I am always careful and use the latch loop on the hood to pull it down. I'm sure if the deflector is tugged on when the hood is open enough time the tape will give. When it's closed it's very secure.