I actually still think Hiei could win unless Pain pulled a Chibaku Tensei from the start. Hiei's physical stats after absorbing the Dragon were probably better than Sage Mode Naruto's and his DODF could probably wipe out most of the paths in one go.
Actually Hiei did it 3 times. He blitzed Seiru, he blitzed Sniper and he blitzed Makanatro (I don't remember how to spell his name). 2 of them ending in instant wins. The 3rd time was when he took off the arm before anyone even noticed.
People saying hiei doesn't speed blitz IC really need to reread the series. Like taichokage said, he does it several times. And even if he doesn't, pain won't be using chibaku tensie ICunless he's desperate.