But even he gets that in high demonic form (Super Sparda form in DMC2) Dante is faster etc than is his regular demon form. That aura that he gets when he first transforms into the form close to his father's (and which you also get with costumes that give you unlimited DT- proving that the stuff is canonical and the aura appears in relgular DMC storyline also) is clear showing that our handsome whitehaired halfblood finally becomes true high demonic lord and a heir of his father's legacy.
So I don't see why he wouldn't choose that form for fight since it's within his powerset. Both he and his dad (going by Mundus' saying that Dante's eyes shine exactly like his father's ones) were able to deflect powerful destructive spells with just their eyes. Imagine them deflecting Inspire Hate on Kain's teammates. Fun, anyone?