I understand what both George and Chris are saying. However, I do have a fear that arguments such that one should not give up practise, because that is when you are about to develop the most are flawed.
The same type of arguments are used in other religions to make sure people stay with the institution e.g. in Christianity people will often say it is the devil who is tempting you away, and that you must resist to get over this period.
As you may have realised from my original question - I have changed my attitude towards enlightenment, and I reject systems which insist on indoctrination. It is true that there are some things you can never understand until you have passed through them - but similarly there are many deluded people out there, and to me, my spiritual beliefs would have to be based on a consistent 'truth' laying at the base of all things.
I suppose I am interested in Zen partly due to its acceptance of death and extinguishment of the ego. I have no real drive to practise zen because I no longer have any desire to be enlightened (and usually have little fear of death); just to be spiritually satisfied. I get a strange comfort from the fact that, no matter what, one day I will be dead (as will we all), and my actions will have no real (extrinsic)meaning.
If the situation arises when I fall into a zen practise with which I feel comfortable, maybe I shall do that. If not, I won't. I do hope people are not practising zen to escape samsara; which I just see as the eastern equivalent of being good so that you go to heaven.
I am sorry if any of this offends people - I can only speak from what I feel (everything else is other peoples words).