Then I guess Pain should also get his legs back which he lost in the ambush by Hanzo. But you are forgetting a very very important fact Itachi's loss of vision was direct result of overuse of sharingan and chakra loss Itachi felt was not just because of sickness- that's again side effect of sharigan- Uchiha body could take more off it off course. Kakashi always ends up in hospital after using it being a non Uchiha. Sickness was killing Itachi. But you can't negate direct effects of Sharigan.
And we don't know what could Pain do at full power either. He almost started his carrier as a cripple. Duh. Pain still remined undefeated.
Huh? Where? In which context?
O.O I think that not only the whole bunch of Akatsuki, but entire village of Konoha shinobies would be pure idiots if after getting the whole village reduced to rubbles they would ask proof of Pain being any good.
Only reason Itachi was able to infilterate the village was that he was former ambu/root. He knew how village security worked.
I don't think you understand the words Deva, Naraka etc that well. They belong to eastern mythology and sometime some of the meaning is lost in translation.
The six realms Kishi adopted are from Buiddhism.The Deva realm is the realm of bliss .
The Deva realm is sometimes also referred to as the gods' realm, because its inhabitants are so powerful within their own realm, that compared to humans, they resemble the gods of Greek or Roman mythology. However, while the Devas may be referred to as gods, they are not immortal, omniscient, nor omnipotent, and they do not act as creators or judges at death, so they are notably very distinct from the Western concept of God.
And you are not...
Agreed.

And I have no reason to believe Nagato as a lesser user of it- he didn't even use to go blind when using it.
Off course he ran. Only an Idiot will stand in the way. You wanted him to pull a Raikage? Wouldn't Itachi dodge a shirkage thrown at him?
Pain didn't run away for good like Madara. He pulled back and launched another attack on six tail he thought would work.
Tsunade didn't exert herself for the fun of it. She was forced to. Pain had no personal vendetta against her to go after her. When she tried to attack him, he blew the village.
Itachi also said Jiraiya would beat him. What's the big deal? Important thing is that Pain didn't give Jiraiya enough time to beat him right then. Game over. This argument is neither here nor there. Much good this information did to whole of Konoha. Even Naruto was tired even though he knew the great "secret".
How he beat Hanzo isn't even important. First time Hanzo had escaped. Obviously scond time he couldn't. That's all to it.
How many fights we saw him in? You mean fights with ordinary jounin like Kurenai... yawn. He was a s ranked Akatsuki. What did you expect?
Jiraiya was able to trap him in toads belly along with Kisame. He escaped using Ametsrasu.
They were all Uchiha but they were all powerfull? Not evey Uchiha carried MS like Itachi. Madara helped him out to top it. I wonder how many Itachi actually killed or he just took the rap for Madara. Madara who with his unique technique is able to appear and diappear anywhere.
Shishui's death might have given him MS but, that's neither here nor there. It's got nothing to do with his ability to fight against Pain.
What debate?
Good. you know the basics. Now follow it.
Itachi was not pretending anything. He was just keeping his mouth shut.

Yeah, he meant no harm to Konoha. I am not so sure about its shinobies. If Itachi thought that taking out a few shiobies would save rest of it he would do it. Uchihas were konoha shinobis too.