Pass Labs Class A Amplifier Meter Reading

i believe your understanding is basically correct

although papa nelson says emphatically in his past writings that the class a to class ab transition is not a finger trigger noticeable transition, it is in fact very subtle in practice once music is playing... almost imperceptible (otoh clipping is VERY noticeable)

his view is that the key in great amp design is to have fairly high class a bias to keep the first few watts delivered very pure and low in distortion - so i think the idea of having the bias meter move occasionally on musical crescendos is quite alright

have owned a few Pass amps and you are correct...on some of the amps it hardly ever really moves...it's not meant to be an exact indicator 

Correct. That is a bias meter. 
On my XA-30.8 the needle normally sits just before the center 12 o’clock mark. 
When the amp transitions from Class A to Class A/B the needle starts moving past the 12 o’clock mark. Within normal listening levels in my system (82-92db) the meter does not move. Push it hard and that needle starts dancing. The amp remains composed and sounds great. It depends on your speakers, the size of your room and how loud you listen. 

Thanks for the replies.