This thread makes me laugh - it's so pointless....
99% of it is simply regurgitated info/opinions that have been done a death on the other BA thread. The remaining 1% is the cadet who's lucky enough to be going to BA as their first job, asking about rosters?! As if there's even the tiniest chance they'll not go to BA because of any answer given. Personally I'd just concentrate on passing your training first time and worry about the roster in BA later. It's a legit question I'm sure, as there's nothing wrong with trying to plan your future a bit, but as has been demonstrated above you need a type rating in BA's rostering system to make any sense of it from the outside anyway.