Definately agree with the idea of doing a full test instead of the CBT. You have no questions about highway code and no real experience on the open road apart from 2 hours which is rubbish.
I did a DAS last June when i was 26. It was my girlfriend that entertained the idea of me getting a bike as i had always um'd and ar'd about it because in my head i could never get past the fact that with 2 tyres only there is much more of a chance that you wont get round the corner.
Now i have a bike i love it and wouldnt trade it for anything.

Back to the subject though, I had 10 years road experience before getting my bike so when i get on it i am learning how to ride the machine not how the road works and that takes plenty of brain power. If you have to learn the road, what other people are most likely going to do and learn how to control the machine i cant see how anyone can really do it.
I think the age to control any machine on the roads should be 17 and you should have to take a full test to drive it.
DAS shouldnt really be allowed unless extensive road sense can be proven as most people can drive something but not many have road sense.
I have a 750 after 9 months and although i love it i think people should have to have something smaller than 80BHP for one year and after that it is yours choice.