Whether or not stir plates provide any appreciable level of aeration (either before or during active fermentation in the starter) is a topic I have seen debated almost endlessly. Are you aware of any studies on this issue? I'd love to get a definitive answer; all I've ever seen is conjecture.
It doesn't seem like it would be a difficult experiment for someone with the proper equipment.
I found this and posted it on the forum quite some time ago. There's probably more information out there somewhere.