Yup, if you have to lose speed anyway it is better to cut off the fuel completely and have the engine do the braking than spend fuel on idling and wear out the brake pads.
Then again, the Insight has the mother of all DFCO's by setting all valves wide open and even give electrical assistance when needed; I can coast down for almost a mile like that
I even have to select Sports mode to get real engine braking like when descending a hill. That's theory so far; up till now I have not yet taken the Insight over 100 ft above sea level. In fact, it spends most of its miles below.
__________________
2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gmeter or 0.13 Mmile.
For confirmation go to people just like you.
For education go to people unlike yourself.