Akuha won't exhaust herself that easily and using the Jigentou has much more applications for use at a lower power output so she's not going to go full bore from the start. Neither is him blocking it going to give her a hernia.
I have a feeling that you need an equal amount of power to the Jigentou in order to block it. If that's the case, if Akuha engages in a 'horns locked' battle, there's a good chance that Tsukune's energy will run out faster than Akuha's from the constant drain of trying to keep her attack from hitting him.
The only way she'll truly lose control is if she sees just how much Moka favors him above everything else. And to learn that Tsukune is not only 'above' her in terms of 'importance' but also a human whom is infused with the Shinso Blood - I think that revelation will make her 'snap' into something far worse than anything we've seen from her as of yet. So far, she's been overbearingly powerful and even against Todou Fuhai, one of the Dark Lords, she was relatively calm. Akuha snapped will probably be one frightening moment to behold.
And on a different note, Rubi's mini-boss seems an awful lot like Raizen from YuYu Hakushou...I guess it's the hair and the lightning.
Too bad that Mizore's ice clones are almost useless here - Gyokuro can see right through them. Depends on how she uses them though - using them to run around a corner to trigger an ambush then the real ones follow up. Would be a nice tactic if the other mini-bosses didn't have good sensory skills, which they probably do. ...I wonder if Sun's voice can disrupt Gyokuro's sensor ability... If Gin and Haji camp out near her location, she's good to go on anything.