minato is genius in every sense you can mean it or take it. his silly sense of humor and hashirama like spirit can sometimes cause a false impression, which is a good thing if such personality traits were among things considered when an opponent were to size him up! (if raikage were to underestimate him after hearing a ridiculous jutsu name for example).
tobirama/second hokage makes seemingly unfair yet authoritative remarks about minato (sometimes lumped with naruto) because he is conditioned to treat such personality having been conditioned by his upbringing and relationship to his brother, hashirama.
tobirama will naturally talk down to such people no matter their level of superiority or sheerness of their genius.. it is something that should be its own study and discussion for tobirama but it's sad to see it create confusion regarding minato because like hashirama and naruto, he is sort of like a "hakuchi".. a white knowledge pure of heart kind of guy without intellectual impairment (contrarily, is gifted). tobirama has a very cold attitude that can steep into negativity when necessary. such personality is sooner and more immediately burdened by impending horrors and must deal with such problems in the harsh ways it has limited itself to seeing. when you pair such a person, in battle, to a partner on the opposite side of the personality coin... you get the picture.
more than the recovered hokages or kakashi's vital signs, i am mostly curious of orochimaru's motives given that he is currently mirror to sasuke in the whole "i've changed" dept. kishi has played the character well enough to keep me guessing as to who's train he will ultimately hijack, madara's or sasuke's... especially given that his aim during the time-skip period saw far ahead enough to deal with the critical elements currently at work with just about every major player. to a lesser extent, kabuto.. and what specific impressions he has made on orochimaru since being "ascertained" while immobilized.
minato may have used the cloak simply as a display for the sake of naruto or to grandstand (similar to how jaraya does). like paulbee, i don't think the cloak has been the sign of any sort of powerup or other benefit so far with minato's abilities. the best case, though, appeared when he wanted to enhance one of his more powerful techniques but was deemed unnecessary or ridiculous by tobirama then preempted by naruto and sasuke. i am of the belief minato has not been operating on a level different than if he were simply giving his best as a living hokage without sealed 9tails chakra. last thing i will say about the chakra is that instead of being a means to powerup, it could simply be radiating from minato no longer having the concentration to suppress or properly manage things with his seal and the seal is doing all of the heavy lifting and working as intended. the mechanics are not 100% identical to naruto's circumstances. i simply dont see minato being powered up by fox chakra yet.