What are the correct settings of RF Gain in 6600M?

In the manual for the 6400M/6600M it states that the RF Gain below 12M will generally be set to 0db for greatest dynamic range.   IN Sherwoods test results he states, "Test data for 6600M is after May 2018 PEN (Product Enhancement Notice). Due to the insertion loss of 7-pole bandpass filters on the contest bands, recommend +16 dB preamp during daytime on 80 -17 meters if in a quiet location. 15 - 6 meters may require +32dB preamp for an adequate noise floor".  How are users setting the RF Gain and what are your results?

Thanks  Bill--K5ZQ