That is not how efficiency works: Efficiency boosts your power levels based on your power level SETTINGS. Any additional power gained by skills and other abilities does NOT reduce the amount of power you gain from it, only the raw 100/50/25/25 settings count. If THAT value is under 75, you will gain an Efficiency boost....it does not matter if spells and skills are boosting those levels above 75, you will still get a bonus if your setting is below 75.
I think they should make Reroute Power abilities that are universal and allow you to change the power bonus ships have for example change a science ships +15 Aux power to +15 weapons for a short period of time. Ensign lasts for 15 seconds Lieutenant lasts for 30 seconds Lt. Commander lasts for 45 seconds. Cooldown use time of 60 seconds when fully improved. Just a idea