You are completely delusional if this
http://www.mangapanda.com/naruto/641/4
isn't Tobirama using it with no hand signs. I'm sorry but there is no other way to put it. Also the jutsu says that it allows two Hiraishin users to mark each other and then swap positions at any time (which Tobirama also clearly did with no hand signs). Tobirama was holding Obito so he teleported with him into the attack that hit Minato.
I can accept being delusional regarding Hiraishin no jutsu. Not like I'll have to fight any users of it anytime soon.
And Hiruzen is not a Senju-Uzumaki hybrid, so it might explain that it would take him a little longer to regenerate. Come to think of it, the other previous Hokage were only Senju, but ya get the point.
A fight with Hiruzen at full strength... Yes, Kirk, I agree, that would be awesome to see! Even if it moves away from the 'main' fight that is going on.
And Oro and the Kage are on the way. I'm sure they're kind of slowed down just a tad, I mean, Tsunade did get ripped in half in previous chapters. Probably doesn't wanna rush it, might make a few stiches come loose. xD