Madara vs Itachi

[Unorthodox]

could go either way

 

[USSJ Future Trunks]

3T Itachi was able to fight on par with KCM Naruto.

madara fought on par with hashirama for years when they were teens.
and no naruto wasnt even remotely serious.

 

[AGoodBoy]

Sennin mode enhances his perception to read movements and react to them in time [

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]. It allowed him to read Juubito's movements and react to them. It doesn't matter if BM made him faster. SM still makes him react and Naruto couldn't.

Yes, SM allowed him to read the movement, but BM is what allowed him to move his body fast enough to even attempt to intercept. Like lee said, it doesn't matter if you can read your opponents moves if your body can't keep up.
In any case, juubito still blitzed bsm nardo[

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]. So, he's not immune to being blitzed U_U