Yes AB bias will actually have higher gain, and yes it takes more DC power to do it.
Class A ( or in this case AB or B) is not as efficient RE current draw per watts RF produced, but I will tell you that class A will reproduce the best signal out compared to the signal in.
This is true in both RF and Audio.
This is mostly fueled by competition type operations where every DC amp must be used to make the most raw power, regardless of what it sounds like in the end.
It is a age old debate, it has been beat to death and those who understand RF know the answer.
On the Air, it sometimes seems that even if the signal sounds like shit, operators will give a 5/9 because if they say something sounds wrong, the station will reply that it must be your stuff screwed up, because this is a new amp, and it is rocking my wattmeter.
Even if you could show every operator how trashy it looks on a S/A they will still blow you off.
To many, if you are not splashing 15/20 channels you are not 10-8 and smoking.
Not everyone, but some.
73
Jeff