Well it is. The only way to get out 9-tails (and score the game winning effect) is 2 ways (that i've heard/seen):
Use on T8 to get out (Six Tails) and next turn go into 9 Tails. simple, the only trick is getting Naruto above 7.
Use the Masked Man into 9-tails combo you mentioned, along with the new Haku Hakus clone of 9-tails will still have the effect to win the game when PiP. The trick with this combo is Haku requires it must be 2 water, and MM's handcost means you'll want decent amount of Fire, so bare minimum you're playing Fire/Water deck. (then there's annoyances like Shimon or *insert any ninja negate*)