I agree, I think Hitler was at his sharpest in the mid 1920's to mid 1930's when he was struggling to get into power.
I also think this version of Hitler is generally smarter still.
To riff off the DND cartoon post, in the OTL game he leveled up on Charisma, especially the kind that works best on the ruling class; here he has been neglecting that but his points go into Intelligence instead. I note he's using radio--perhaps that step is the one that prompted the letter from Lenin--but I believe his appeal here will be curtailed on a class basis--fortunately for him he remains of some appeal to the biggest class! But he's going to get nowhere hobnobbing with the great and good, or only with people who admire sheer ruthless self-confidence and bravado and don't care about bourgeois manners.
I believe though he has a clearer, more truthful insight into what goes on and how things work and this may prove an asset versus OTL; also I think he is more stoic and self-controlled; to a greater degree he remains the disciplined corporal accustomed to the stress of battle and with a greater situational awareness.
All that said, I am not sure he really should go to Moscow, not at this crucial moment--of course by consensus a Marxist is not supposed to believe in the essential role of one individual; in theory the Red Front should progress as well as it could with Hitler in charge with some subordinate running it for him while he's away. There is some risk of losing momentum, some risk of capture or death by accident on the way (sure, he's traveling under cover of the German General staff backed secretly by the highest authorities in Weimar--just how much security is that worth though?) or if the Bolshevik politburo decide they don't like what they see.
I think Hitler's core nature does guarantee he would take all these risks though, and go. Whatever Marxist doctrine he accepts on an intellectual level, deep down he still believes as a matter of unquestioned faith that he himself is an essential figure, and that his personal worth is gauged by the courage to take risky chances that have the potential of giving him more power. The former intellectual knowledge will enable him to mind the sort of Ps and Qs that Bolsheviks care about--he won't say anything about the "Leadership Principle" at least not as some ideal thing; he might work in some remark about the need for bold leadership of the proletarians that will pass muster or even earn applause from Lenin's inner circle.
In general I think he will be disappointed and disgusted with shortcomings in the USSR--much of this being unconscious prejudice against Russians, Jews, and disgust at Russia's poverty and disarray that he consciously thinks he has risen above--and he will come home with a simultaneous resolve to work with the Third International and project loyalty to it impressively for now, and to break free and go his own way when the time is ripe, and he will run the Party in Germany with the hidden intent of avoiding what he feels are mistakes the Bolsheviks made--but never say anything hinting at his reservations until the day when the International is more trouble than it is worth to him comes. (Or by then, he might even see a way to try to hijack the International from Moscow's control, and perhaps succeed in splitting it).
I am not sure he'll ever be working with Stalin, leader to leader; the breakaway might come earlier than Stalin is acknowledged supreme Soviet leader. In a short visit to Moscow he might not even realize Stalin's future role--Stalin was able to hide his ambitions from Lenin after all! Although both dictators have some overlap in methods and style, they are also quite distinct. At this point in Moscow and around the USSR, Stalin is projecting the image of a steady, hardworking and loyal follower of Lenin, a team player, not a would-be supreme lord. Indeed far into his ascendency when he had already achieve an unassailable position a decade and more hence, Stalin continued to play the role of being quiet and unassuming; during the high Party purges he would let others do the aggressive attacking of the designated victim of the month--and only come in at the end to quietly observe the consensus of the Party. He posed as someone not entirely too bright who humbly wracked his brains to ask "what would Lenin have done?" He fully understood the egos of other ranking Party members, how to stoke them, how to sneak around them, how to turn them into weapons against themselves, that the Bolshevik leadership was plagued with jealousy and petty feuds, and how to stay out of their focus while he set the dynamics up like pool shots. Hitler could hardly ever play any such games; in this respect their styles were quite different. If Hitler were in fact working really closely with the Moscow Politburo I suppose Stalin would maneuver him into a position to be taken out.
I suspect over time, observing Moscow as an Internationalist from afar, it might become apparent to Hitler what Stalin is up to before it seems clear to most others, but at arm's length in Germany I don't think Stalin could set him up for a fall and might not realize the necessity of trying to do that until it is too late. Perhaps the two will still work out a face saving formula that keeps the appearance of a continued union of USSR and Hitler's Party, for the sake of fooling the global bourgeoise and other mutual benefits--much as there was no appearance of a breach between USSR and PRC while Stalin lived, even though Mao had never been Stalin's favorite and did things such as jump into the Korean War Stalin would rather he did not--the general pattern of Third World ragtag revolutionary parties wagging the Soviet dog was apparent enough after Stalin's death. Generally Stalin did not tolerate deviance even overseas and would sacrifice a viable revolutionary movement to his demands for kowtowing to the orthodoxy of the day, but with a sufficiently powerful German movement he might be forced to make exceptions!
Fundamentally then, I expect a breech and Hitler will in the end go his own way--but it is possible that this breech might not be apparent to the eyes of outsiders!