You make sense. It's just that when we go by creating hypotheticals of feats it boils down to opinion. You'll give a scenario based on your views and someone else gives a different scenario that is also reasonable with their views, and then it becomes an endless circle of discussion.
I'd rather just go with the plot than creating hypotheticals in my head. It's too much of a hassle for me otherwise, and it allows me to not create too much expectations of how fights will go down. Surprises are always nice.
Some conclusions are arrived at using simple common sense. It's like trying to debate who is stronger between Moegi and Hashirama. The answer for that question should be obvious, similar to a myriad of the hypothetical match ups that people create.
Also, I wouldn't be surprised if Sasuke unleashes perfect Susanoo soon, it's just that as far as the current plot goes he still doesn't have it. If it happens next chapter then we can say that Sasuke had it since chapter 661, but that's about it. Speculation is ok, but let's also remember what the facts are and see the current situation based on that as well.
Just to be clear, I'm not saying that Naruto can definitely beat current Sasuke without Kurama, I'm just saying that it's an existing possibility that shouldn't be brushed off completely, going by the plot.
In this specific situation, Naruto being inferior to Sasuke is plot based. Since his statement was introduced, there have been no contradictions or developments to argue that he might have surpassed or equaled the level that Sasuke is at currently. You would be playing the devil's advocate if you made an argument that contested against what Kishi had Naruto state. That is, if we look at the situation through plot centred lenses.