@luthluth: By the time they come to that conclusion, it's likely a good chunk of their forces will already be wiped out. Still I won't rule out the possibility of it happening, I just think they would resort to Kido and hax before sealing techniques, but that's subjective.
OP says IC.
That being said, Yama has proven time and time again that he's too arrogant to use bankai from the get go, and he say words of wisdom before actually doing shit that takes time, time he doesn't have when fighting someone like Kizaru, other captains are like that too.
Admirals on the other hand are professionals and will do shit right away, but they often let the opponent attack first.
So the fight probably will start with the captains babbling shit to the Admirals, haki will then kick in and the Admirals will know who/how/where would the captains attacks, and would proceed to counter-attack, Kizaru alone would probably take out the lesser captains, Aokiji flash freezing the others and Akainu would most likely go one-on-one with Yama. Yama would probably use bankai at this point seeing that his comrades fell to highly capable opponents, but he won't have the time since Admirals don't just watch as their opponent tries to power up.
So, I say Admirals win due to primarily CIS.
And about Kizaru having a long hang-time, he probably was just floating because he's light, since light has no mass, he's basically no-selling gravity.