[Elecraft] K3 transmitter gain setting?

[Dave G4AON]

Following the release of the latest manual, I note the emphasis on 
needing to set the transmitter gain on each band, at both low (5W) and 
high (50W) power levels. What isn't clear is whether it's preferable for 
those with an _accurate_ Wattmeter, to set the gain based on the K3 
display or an external meter. Having previously set the K3 power 
metering on the 20m band, the differences per band are not great and 
perhaps academic, but I would like to know which is the best method of 
setting the gain as the manual doesn't mention using an external power 
meter at this point?

For what it's worth, I used an LP-100 power meter and set the gain for 
the power as indicated on the external meter. Having set each band, both 
at 5W and 50W, exited the menu, etc. The power levels were within 1 Watt 
at the 50 Watt power output setting on "tune" on every band... The 
LP-100 is a calibrated unit and within 5%.

Dave, G4AON
K3/100 #80