Or asked another way will
[CLLocationManager isMonitoringAvailableForClass:[CLBeaconRegion class]]
and
[CLLocationManager isRangingAvailable]
ever return different values?
Short answer: No, there are not any iOS devices that can monitor iBeacons but not range them. Both methods will return the same value if isMonitoringAvailableForClass is given a CLBeaconRegion instance.
The reason the API looks this way is because the isMonitoringAvailableForClass method can be called with classes other than a CLBeaconRegion class. CLCircularRegion is used for monitoring geofence regions. The method might return NO when passed CLBeaconRegion on a device without LE Bluetooth, and return YES when passed a CLCircularRegion on the same device.