The free will excuse used to explain how perfect Adam sinned, is foolish. Think about it, why does anyone choose to do wrong? I can think of 3 main reasons (though there may be more):
~ Ignorance.
~ Lack of wisdom.
~ Lack of self-control.
If Adam and Eve were made perfect, they would not have had a lack of self control. What about wisdom? Being perfect, Adam and Eve should have been perfectly wise. However the extent of their wisdom would have been limited by the extent of their knowledge or ignorance. Being new to the world we can assume that they were ignorant. It is this ignorance that caused Eve to be easily deceived by the serpent because deception works by exploiting a person's ignorance.
But who was responsible for the ignorance of Adam and Eve? Doesn't every parent have a responsibility to educate their children in the best way possible to safeguard them against being misled by bad peers? Did God do all he can to educate Adam and Eve sufficiently so that they would be personally convinced of the wisdom of doing what is right and not disobeying?
The bottom line is that people choose to do bad because they think they will benefit from it in some way or because they lack self control to resist doing bad even when they know it will ultimately harm them. But if God made them perfect they would have perfect self control; and if he gave them sufficient knowledge they would not think see the doing of bad as being a desirable choice. Therefore God bears responsibility for the sin of Adam and Eve.
Free will is not absolutely free. It is governed by the environment. God created an environment that led Adam and Eve to the choice of sin.
Do normal, healthy people choose to jump of cliffs to their deaths? No, because they know about the effects of gravity and so that choice is not desirable. God could have implanted Adam and Eve with all the knowledge required to prevent them from being deceived by the serpent. Knowing all the facts they would have chosen of their own free will, not to eat of the fruit.
So the idea that one can't have free will without the possibilty of sin, is in my view, a fallacious one. God has free will. Does he sin? No. Why not? Because he is not ignorant. He has enough knowledge to be personally convinced of the value of righteousness and this makes the choice of sin an undesirable one. Thus one can have free will without the possibility of sin.
So if I was God, I would have implanted in Adam and Eve all the knowledge necessary for them to fully understand the harm that doing wrong ultimately causes.