With all due respect to the Russian League and French League, they are too small for a player of Ronaldo's stature. He will never be in contention for the Ballon' D'or or World Player Of The Year awards being in those leagues if you ask me.
The only issue for me is that Madrid will want the next big thing to replace him, and thats is Aguero in my opinion, and I really do not want him going anywhere. My only hope of us getting Ronaldo and keeping Sergio at the same time is that Sergio would lose all his love from the Athletico Madrid fans, he won his fair share there so I cannot see him wanting to be hated by the club that made him star and brought his name to the world stage.
I would have Ronaldo in a heartbeat and his shirt sales, merchandise etc etc.. would cover most of his fee, his wages would be killer though.
The big questions is, how much loyalty does he have remaining at United? Soon as he signs for City, United fans will despise him.