You will not notice a difference in flying qualities if the servo had plenty of torque before addition of the tab. The least expensive experiment might be to try to do several "identical" flights with and without the tabs, each starting with a fully charged battery, and see if the battery is "fuller" on average at the end of the boosted flights. This might not be conclusive if the difference is small, the temperature changes, etc. Otherwise you might need a recording of in-flight current draw. If the difference is so small that you can't tell a difference this way, one might argue that they don't provide enough benefit to be worth the extra trouble in your particular application, though they might provide some increased life to the servo and/or battery.