Yea, I applied the wrong formula...
But I suppose the problem is that in F=ma the a is the acceleration, assuming the objects falling have near nil gravity of their own.
Well, I looked up the definition for "fall" on Wikipedia (though not truly an authoritative source).
"Free fall is any motion of a body where gravity is the only or dominant force acting upon it, at least initially."
And the problem is that a single "body" is described, and the force or acceleration produced by that body is not taken into account.
I guess the point I was trying to make, is that that definition is not balanced, in that it considers gravity for one object where two are involved.
That is why in my example I placed the falling objects at opposite poles, to demonstrate the idea I had in mind. The feather would be along for the ride, but it would it's landing would be the last to take place. Granted, it's not a common situation that would usually occur... :p