Firstly, though I don't believe Jesus was Michael, I have no axe to grind with those that do. If, as Earnest suggests, it is merely a title rather than a designation of substance, there is little problem with that. I tend to go with Didier's view that there were several Archangels, however, and so that position precludes Jesus being of this class from a Trinitarian perspective.
Its my belief Jesus was not in heaven when he was on earth...
That wouldn't be my view, as it presents a problem with Trinity.
I prefer the opinion that he "extended down" to earth, choosing to limit himself, whilst remaining fully in union with godhead.
Of course when we talk in terms of omnipresence the question becomes moot anyway.