Regarding the sim prep vs no sim prep debate....
I would like to contribute to this debate with my own experience if I may.....
I did the BA selection a little over 2 years ago and got through to the sim stage but failed that. I have just done it again this year and passed this time. The difference - no practice in a sim the first time vs 2 hours PF + 2 hours PNF this time.
I understand what people say about the exercise being primarily about how you and your colleague work together, but there is an element of assessing the flying - it says so in the sim brief! It also says they assess capacity - if you have none because you are concentrating so hard on flying straight and level it will be noticed.
I am an airbus bod at the moment, and spent 4 hours in the 737NG sim at Horsham that I talked about previously in this thread. This practice gave me enough manual flying and handling a Boeing MCP to allow me to contribute to managing the detail while manually flying the 747 sim during the assessment. If I hadn't done it there is no way I would have passed. No matter how you prepare mentally or on the PC, the power / pitch couple when flying the 747 will undo you if you have been on an airbus for a number of years like me.
Different horses work for different courses, but everyone I know who did even a little sim prep has passed the sim assessment with BA. I think it is probably only those who passed with no sim prep that speak up against it. It would be interesting to know how many who didn't do any sim prep didn't pass the assessment. However, that is not something one advertises on here too readily. Those who want to do some prep don't be put off by the whizz kids who can pass it without preparation. The rest of us are mortal.
The course I did on the 737 sim at Horsham was the difference between me passing and failing the BA sim assessment - simple as that. And no I don't work for them, have shares in their sim, sleep with them or anything else the cynics will suggest.............Good luck all.