I think naruto will be able to control half of fox,s chakra it is difficult to handle such massive chakra we see that killer bee is an adult and he can control his beast but naruto is still teenager. 9-tails is most powerful of all beasts because he has max number of tails. naruto will control it when he become little older.{REMEMBER}WHEN KEY TOAD WAS ASKED BY JIRAIYA "TOGIVE THIS KEY TO NARUTO IN previous episode when jiraya was going to infilerate RAIN VILLAGE.THEN TOAD SAID THAT NARUTO IS NOT ABLE TO CONTROL FOXES CHAKRA HOW WILL HE ABLE TO CONTROL YOURS. SO NARUTO HAVE THREE POWERS 1-FOXE,S POWER 2- JIRAIYA,S POWER 3- HIS MOTHER,S HIDDEN POWER. WELL this is all how i think the original story will be of course more thrillng I THINK NARUTO IS MOST GIFTED NINJA EVER EXISTED.