If enlightened beings exist, one must wonder if it is possible to meet them in the Orders. Considering what I know about enlightenment, which is not a lot, I would have to say yes. It is possible for a person to use the tools and methods of Golden Dawn to access mental states that are normally barred to us.
Now does that mean that those members higher in the Grade structure are more enlightened than those below them in Grade--NO. One of the misconceptions about Golden Dawn arise from the correspondence of each Grade to a sephirah, and each sephirah to a mystic experience or state of consciousness. Some people believe that the mystic experience comes automatically with the Grade; this is a belief that Mathers seemed to encourage based on my understanding of his writings. One of his students, and later enemy, Aliester Crowley also encouraged this belief. It is wrong.
I have seen no evidence that the mystic experiences automatically come with the Grades. The Grades are the gateways and stepping stones to those experiences; they are not the experiences themselves. A certain amount of work must be done to realize the full potential of a Grade; a person must work to unfold the mysteries of the rose, or any of the lesser Grades.
Nevertheless, occasionally one does run into someone who has gained the vision of the machinery of the universe, or insight into sacrifice, or whatnot though the tools of the tradition. Most, if not all, of them keep their attainment to themselves. Beware of anyone who brags about their knowledge, enlightenment, or Grade; normally, such boasting is the sign of a sure fraud.
Occasionally, it has been said that the tradition is guided, and sometimes outright led, by people who have became enlightened. To be frank, this puzzles me. What possible use would an Order such as Golden Dawn have to an enlightened being?
Even if at their moment of enlightenment, they chose to come back and guide other beings into the Light, wouldn’t the trappings of our tradition be more of a hindrance than an aid to that pursuit? And how hard would it be to hang onto your enlightened state if one was forced to be the head of such an Order?
Thoughts like these affirm my own personal belief that the Golden Dawn tradition is not so much about enlightenment as it is about magic. It is not that enlightened beings are barred from joining the tradition (though I know a couple of Orders that would expel them the moment their leaders caught on to the fact), or that spiritual development can not happen inside the Order--it is merely that it does not seem to me, at least, to be the ideal vessel for this to occur.