Here's a question... what are you doing getting vectors to begin with? VFR and outside of Bravo, what gives ATC the authority to give you these vectors in the first place?

For the first and original argument, I'm still undecided. Whether or not you automatically gain a Bravo clearance upon canceling IFR in Bravo airspace. I would obviously assume so, but from a legal/FAR standpoint, I'm not sure.

As far as the second argument, I'm going to with the "Cleared to/into...." crew. A heading/altitude assignment, in my opinion, does not trump "those magic words." ... in the VFR world anyway.