Can't comment on which type they use these days. However I can comment on the first bit. Don't believe those people. There is no truth in it what so ever. Even looking from an economic point of view, the assessment isn't cheap for BA. Why let people go through all the stages of the selection if they only want rated people to save costs while we need people ASAP. I guess for those who unfortunately didn't make the grade this time around it is easier to blame it on the system.
During the assessment they will verify the earlier assessment stages (your personality), see how you interact with your colleague and lastly how quickly you can learn new things.
From what I remember when I did it, it is hard work however the instructors are going the extra mile to make it as pleasant as possible.
Good luck!!!