Tough question.
You see, the brain has it's own "divisions" so to speak. Every part of the brain has allready been at every level before we start meditating. However, let's say an artist is really good at painting, while painting the creative part of his brain that is involved in painting will probably allready have reached Theta, the brainwave that is most creative. The rest of the brain however might be active in Beta or Alpha.
What we are talking about in terms of brain entrainment is made with
Whole Brain Synchronisation, which means that the whole brain is trying to establish communication between the left and the right hemisphere.
This is such a unique process that I seriously doubt that anyone will have experienced this without brain entrainment, no matter how experienced the meditator.
So your question is a bit academic in my opinion, because the LifeFlow technology helps you to achieve more successfull whole brain connections during meditation, and as such you are, no matter how experienced you are a meditator, only a rookie, and have to start from scratch.
for more info on brainwaves check out this thread:
Brainwave States