Hunch, we all know GL300C has lower Tx power, but 300A & B are equally RF powered (more, they have even the same FCC ID). Why would you then rather preffer the A than B ? Asking since you obviously have a lot of knowledge in this field of UAVs.
Normally 300B would pull less battery consumption since it hasn't that Texas Instr video processor, that DJI has concluded it isn't necessary, hence removed it when they evolved this RC generation from 300A to 300B.