Boothy
Don’t be confused. The beauty of having driving training, by various instructors, is that you become aware of alternative ways of driving a particular corner/circuit. The secret is then to practice what you’ve learnt, & then decide which is best suited to you & your car.
Don’t forget that a 20 min instruction session is just that, it’s not a driver coaching course!
Keep practising, but most importantly, enjoy yourself! 
The “B” line does however compromise you down the next straight, you will not be on full power for as long so therfore will not have a high top end, in rocket it would make little difference as there is no straight and in fact it might give you a better line to the right hander, anyone who went out with Gav or does Gav care to comment?
I really like the non conventional line through rocket (it is also in the UK circuit guide) and have also seen the data to suggest that in our cars it can be significantly quicker just because you end up travelling less distance over the rocket complex?
I think the alternate line you describe is the one that Gav takes and I vaguely recall discussing it with him last year as we were doing that and everyone else was going far over to the left before the right hander.
My other favored line is to go in far too hot at the top of the hill so that you run out of road and then gingerly select first gear to rejoin the circuit 
Gingerly - that must be in the style of Sean
I guess the best way to decide would be to take different lines and get some Data and review it after the day, see what works best for yourself.
I had the DL1 switched on all weekend but left the memory card in the car 
would be good to compare as you can see exactly which line was taken at each corner if you zoom in on the track map.