I teach what is in the AIM because that is what is recommended by the FAA. Think about it...if they ask you why you turned at 700AGL, you have a solid reason for the examiner. If you turn somewhere else, then you have to come up with your own reason.

Also, I always contact approach control first when going into C airspace. Why not? They put those boxes on the sectional for a reason: they want you to go to approach first instead of clogging up the tower with people trying to get in who they are, where....all that. Also I have tried this before, and the tower just tells you to contact approach anyway, so you might as well save them the trouble.

It's sort of like shooting an NDB instrument approach...you can, but why? :-)