Once again, asking for that proof.
But you know as much as I do that Itachi intentionally died to Sasuke.. I'm pretty sure everyone knows that.
Few things about the Zetsu point. Even though he knew about Tsukuyomi, he didn't actually see it, so he can't make a judgment on how strong it actually was. In addition, he did not know Itachi intended to die by Sasuke's hands, so he could only assume Itachi was going full-strength (thus, not having a reason to say his Tsukuyomi wasn't full-strength). Now, couple that with his observation that Itachi didn't seem right, he could have made the connection that Itachi's poor performance could have also been the reason his Tsukuyomi got broken. In addition to the point about Zetsu's observation, he could see Itachi physically fighting, therefore having actual evidence to see and claim that something was wrong about his performance. However, he couldn't see the genjutsu battle, so there was no reason to make a wild assumption that Itachi wasn't going all out, and ultimately planning to die by Sasuke's hands.
But here you are suggesting tsukuyomi will be the match decider?
No I'm not, I've listed other ways I think Itachi could take Madara out. We've simply veered towards this particular topic.
both the 3T that broke through it and Itachi himself
Once again you're using the Sasuke example even though the majority of our debate is on whether or not he broke a full-powered Tsukuyomi.
He is shown to be pretty good at genjutsu himself
Doesn't he only have 1 genjutsu feat? Vs Raikage?
because tsukuyomi was broken by someone much less proficient
You KEEP using the scenario we're trying to debate, do you not see the flaw here? You can't use what you're trying to prove as a proof.
Genjutsu =/= genjutsu resistance.
Ehh I think I get what you're saying, but I don't entirely agree with this. What I believe is that in a 1 on 1 scenario, in a battle of genjutsu, the person with stronger genjutsu is more likely to prevail. And once again, I know this will tempt you to say "but sasuke 3T etc etc Tsukuyomi" and I gotta remind you that you can't use that as support right now because that's what we're trying to debate. So with that said, do you have another example to support your claim of:
Someone with weaker genjutsu skill can break a genjutsu cast with a stronger eye because of sharingan mastery/skill.
We can take out the "eye" part because that restricts your ability to find examples, unless eye power is integral to your argument. Because what I'm saying is a person with weaker genjutsu abilities (whether he has eye powers or not) is going to have a hard time breaking out of genjutsu from someone with greater genjutsu abilities (keep in mind I'm talking 1 on 1 here, no help from another entity).