Sasuke takes this people are constantly overrating Kurama because of the things that Naruto has done with it... BM Naruto> Full Kurama... Also it's been proven BSM Cloak is equal to Sasuke's standing Susanoo... He has Perfect Susanoo which has the feat of cutting Obito's DNA sword...
Obito's sword was stated to be a sword of the soul. In other words, when he began doubting himself, the sword got weak. Kind of like a zampakto from Bleach. Also, Sasuke's PS sword was being enhanced by Naruto. How do I know this, because the attack effected Obito, which makes it it senjutsu, which means Naruto's power was running through it. It's not a solo feat for Sasuke.
There's nothing in the manga indicating that Naruto's BSM and Sasuke's senjutsu enhanced susanoo were evenly matched. They were just attacking at the same time. By that logic, Itachi's ordinary susanoo sword equals Sasuke's enton sword.
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Also, Madara himself stated PS rivals bijus. In other words, any concept of a smaller susanoo equaling a biju is false. This also means that a biju enhanced by sage mode is superior to perfect susanoo. viz scan.
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Sasuke's PS is inferior when it comes to power.