Well you see here, Itachi didn't pass the info all he did was protect the village till he was alive which was accomplished no Akatsuki other than him and Kisame went to Konoho and even their he didn't let Kisame lift a finger at anyone. When Itachi died Pein went in. (Itachi deal with the third was that no one else other than him would know about this.) He kept himself away from Konoho and the Akatsuki (He basically wanted everyone to think he was a real criminal and didn't want the truth to get out)
Well it's not Itachi couldn't stand equal to Pein, the problem was that not much of these guys knew where Pein was located and to top it off if Itachi fought Pein he'd have to deal with the rest of the Akatsuki if succeed or failed. (Oro for example he had a lot of respect with Akatsuki especially Sasori after his stunt with Itachi, they all wanted to kill him). Dealing with the Akatsuki would involve in using MS too much which would blind him and wouldn't be able to test Sasuke strength and than die by him.
As you said Itachi was smart and he was indeed, He protected Konoho like he said (After his death it went down in disaster). He wanted to test his borther strength and make him the strongest Uchiha which he accomplished (Not yet but eventually will be). Last he sealed away Oro who would've been a threat to Sasuke.
His only failure is Sasuke returning back to the villages, which didn't happen.
One more thing the topic says if they had full knowledge of each other, that means Itachi as well as Pein know everything about each other and their ability. Winner would be Itachi since we would know Peins weakness as well as Pein would but Itachi has Susanno for back up
well you see here...itachi protecting Konoha was nothing but gud timing,
The bijus have to be sealed in order as to maintain balance in the gedo statue,
so akatsuki was after the lesser tailed beast first
do u think that after all the other tailed beast other than the 9 and 8 tails were left itachi could have stopped akatsuki to come after 9 tails ???
coming to konoha ???
its not that pain was waiting for itachi to die then he would invade konoha..
he thought about the village, wanted to protect it wanted to give a great eye to his brother,
that makes him a gud planner, he was smart and it was due to this smartness that he didnt go against pain coz he knew he had no chance of winning.
so gud timing so that konoha was not invaded sooner,
testing sasuke and givning him his eye..
wat does this prove nething about he being stronger than pain...
these all shows he has a gud heart and all those emotional crap which have
blinded itachi fan boys and made them blind to the ovious reality that pain is
far far superior to itachi on even his worst days