Codestud, I am so sorry that the 12 plus was such a bad experience for you. You are not alone in having suffered long term ill effects. I have a friend who suffers from depression and personality disorders whose health problems date back from that early sense of 'failure' and separation from her peers.
It is important as parents to consider the emotional well being of your children when we make choices about selective education opportunities - and one of the things I like about this forum is that the parents here do put their children's happiness and ability to thrive so high on their list of priorities. A lot of people condemn '11 plus parents' as being pushy and purely result oriented but that has not been my experience on this forum. (Give yourselves a pat on the back forumites!
My DD found out last week that she will not be going to the grammar and the mature and sensible way in which she has handled it has made me admire and appreciate her far more than if she had scored the highest ranking in the county but I do know that her confidence must have taken a knock and there may be side efffects later on. Fortunately she takes music and dance exams regularly so will not have been put off competetive examinations by this one unfortunate experience. DS is still probably going to go for the 11 plus when his turn comes - and I spent some time this morning convincing the mother of a Year 5 girl that she shouldn't be put off applying just because DD's year group had a bad time of it this year.
There's a lot of positives in the 11 plus system and I think people should continue to take advantage of it.