Personally I don't like to calibrate on wwv. I never seem to get it right and end up zero beating on an audio tone. I usually find a stronger shortwave broadcast with voice only. In theory wwv is probably more accurate. I also use headphones when zerobeating as the low frequency response is much better than the speaker.
The main reason that I have switched to the kd8cec firmware as it doesn't move the frequency scale to 10mhz.
I listen to both sides of the sideband alternately. It gets interesting if you have to vary the vfo too much as it moves the bfo off considerable and the sensitivity goes way down. One of my used radios that I bought had the bfo set to the wrong side of the carrier and there was a lot of attenuation going on. He thought that there was an issue with the receiver circuit. As a matter of fact two of my radios purchased use had almost identical operator error.
There are a lot of hams that pretty well panic when the radio doesn't work. It is broke or trashed in their minds. Yet these are many of the same operators who will change circuitry, displays and firmware on their radio before they even turn it on. I like many, test with it stock then change one thing and retest. To my understanding the radio boards are 100 percent tested for function before they leave India. 4 of 5 of the BITX radios that I got were in not running condition purchased used.
Am not being critical of the radio, I really love them. Between my wife (N0BEX) and I, we have somehow ended up with 4 uBITX and one BITX40.
It is a bit concerting to see the list traffic fall off recently. Maybe it is just summer.