Recently installed a an engine analyzer on my 335d. It is the ECO Route by Garmin that connects to the OBCDII port and links via bluetooth to the Garmin so you can see mutiple engine parameters.
Some of those are engine load and air mass flow. Stopped at a red light in Drive I get a slightly higher Engine Load and Air Mass Flow than when I tip it into Neutral. Same goes for the A/C being turned on or off.
So, definitely sitting in Neutral will save you some fuel, but is it worth it? Depends how much time you sit waiting at stop lights.
".......cars don't handle well in neutral during sharp cornering maneuvers when the engine isn't connected to the drivetrain."
Now this had me howling with laughter. Take a FWD vehicle, go into a slippery corner and lift off the gas suddenly. You'll go into trailing-throttle understeer very quickly and slide straight ahead. Now try it but dip the clutch (neutral) instead and the car will track right around the corner. Conversely, lift quicly in a RWD in a sharp slippery corner and the car will likely swap ends as the back wheels skid out (trailing-throttle oversteer). The author of the article obviously has no knowledge of vehicle dynamics.