I cut my engines from time to time...
1. flying low and searching for M3s... kill engine so I can hear
2. Low on fuel and want to make it back to base for what ever reason, climb, kill engines and glide down for awhile, I have flown 10 minutes on 3 minutes of fuel. Not real fast, and doesnt work in a heavy combat environment
3. Need to slow down in a big hurry to land quickly, kill engines, slide opposite rudder, pull back on stick and kill airspeed from 250 to 100 in seconds. drop gear, restart engine for better control and land.