L1A2,
As ASFKAP, I also did my A320 course on VACBE and my opinion on that system is the same. However in 1999 I attended a B737 classic to NG difference course. It combined 'normal' classroom training with CBT in a very useful way. We had the Boeing CBT program and the JMIS(amm,ipc ETC) in front of us on a laptop, and that was very helpful.
I would say that a good instructor is irreplaceble as a classroom mentor, but if you get one of these useless twats from the land of darkness, you might aswell sit in front of a computer.
I don't think you can give a percentage of CBT traing as being safe, there is too many variables, such as student experience and class size.
Brgds
Doc