Comfort and enjoyment at the gig---You are right,that is is great measuring tool.
Its those parts or "styles" of playing that cause anxiety on a gig that are the best indicator of weakneses in ones' playing.
I have found that when I record I will find out my weaknesses the hard way! Especially when the sound engineer says "lets do another take" for the 10th time!
In the past I have taken up lessons with different teachers just following a recording session.
Those recordings are like taking a lie-detector test on the trumpet.(Especially if the sound engineer happens to be a trumpet player who did not get the gig
)