Also, another possible audio change that I had thought of is, when Obi-Wan refers to the force for the first time, Luke responce of "the force!?" always sounded a bit too much as though he had never heard of the force. That always struch me as a bit suprising. While, he certainly wouldn't know much about the force, the idea that he had never heard it mentioned before always seemed a little wrong to me.
In the radio drama, when Mark responds, with "the force" he says the same words, however, the inflection in his voice makes it seem as though the force is something he has heard of, something he was a little curious about, but something about which he had never learned much about. This always seemed a bit more realistic to me, and always made his choice to enlist with Obi-Wan and his defence of the force to Han Solo a few days later more believeable. If it was up to me I would replace Luke's lines "the force" in the movie with his performance from the radio drama.
my .02
Dan Stokes
DDStokes@aol.com