[Ecky]

If you need to coast to a stop (say, a stop sign), the best way to reach there is burning zero fuel, so either DFCO or engine-off coasting in neutral would be equal. Coasting in neutral while idling will burn more fuel.

If you're trying to conserve momentum, look at it in terms of cumulative pumping losses. If you DFCO, you have the cumulative pumping losses of the engine turning at whatever your cruising RPM is, being subtracted from your momentum. If you put it in neutral and idle, you have the cumulative pumping losses of idle RPM, but instead of them being subtracted from your momentum, the engine burns a bit of fuel. Shutting the engine off means zero pumping losses. Overall idle is a net win.

If you need to coast downhill and you need to bleed speed (e.g. speeding ticket risk), DFCO bleeds more speed and you burn zero fuel while doing it.