Susano'o is not a kuchiyose, but chakra that's coming from Itachi's body.
Warped chakra will instantly be replaced, basically.
And you have to remember that Itachi doesn't need to be just hanging out.
We've seen that he can use clones, or that Uchiha can use Amaterasu, genjutsu, etc. while Susano'o is up.
So Edo Itachi can just be spamming shit like crazy.
For a Itachi fan you seem to have missed two of the most critic features about Itachi:
He has low chakra/stamina, very high quality like all Uchiha, but small amounts of it.
and that's why...
He doesn't spam techniques, he devoloped a great sense of tatic and restrain because he doesn't have much chakra to pool from. That's why he's always cool and calm winning his fights with his brain and not with Tech Spam.
My take on the matter is that Minato wins, yet I wouldn't say it would be a good fight.
With no knowladge:
It would start great with both showing up their skill, mostly Itachi showing up his techs and Minato evading them one after the other. Eventually Minato would go for Itachi with his shunshin. Depending on wether Minato marks Itachi or not the fight would last longer or less.
Assuming Minato doesn't. Then Itachi would pull Susano'o up and the most boring and predictable fight would start.
Itachi would be keeping Susano'o up from this point on relaying on mid and long range techs only. By now both oponents would have realized the other is an Edo, meaning only option is to seal.
Itachi will bring out Totsuka blade and might try to use Izanami. Izanami will have the disadvantage that Minato doesn't have a point where Izanami can be build up. Further more this is a no knowledge fight so Itachi wont have the background needed to build a strong moral/psychological dilemma.
Totsuka wouldn't be able to catch Minato.
On the other hand Minato will eventually understand he needs a boost in order to pierce Susano'o which means that at some point he will pull KCM for the chakra boost.
Basically the rest of the fight will be a waiting contest with Minato evading Itachi's long/midrange techniques and Itachi trying to find a way to hit Minato with Totsuka before his chakra runs out.
In the end Kyuubi chakra size pool tilts the fight for Minato. Itachi's chakra would rn out and
The fight with knowledge has two differences. The first is that it would be even more boring because both would jump to maximum power from the start meaning there wouldn't be the first part where both are experimenting techs on each other. It would be a waiting contest from the start.
The second is that now with knowledge Itachi might try to use Izanami on Minato (I'm not sure there is much to go here as Minato doesn't have anything he is not acknowledging about himself, but assiming there is), this means Itachi would have to risk exposure in order to launch the technique which might do the trick for him but might also mean that he gets sealed before he can complete the loop.
So with knowledge it might go either way.
