hashi have sage mode, he can sense kamui and doge it easily
kamui can't be sensed
deva path's rinningan couldn't note that kakashi used kamui on the nail ,although the rinningan should be able to see chakra
when kakashi warped the asingan which hit obito's arm in the other dimension,obito thought first that naruto just canceled rasingan although kakashgi warped the rasingan while it was in fron of his eye ,so sharingan didn't know that there was kamui on rasingan ,because kamui's hole isn't chakra
kamui doesn't travel but appear on the goal instantly ,so it isn't traveler jutsu that can be dodged
about kamui's speed
kakashi warped 2 susano's arrow in no time although his ms was locked when the arrows was going toward him
kakashi warped bm naruto without obito with sharingan notice ,and before obito's stick hit naruto's head ,although it was nearly touching naruto's hair,although both of naruto and the stick was going toward the other in high speed,and although kakashi was performing another kamui on rasingan
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about your other post ,how would kakashi deal with hashirama's 1000 hands jutsu?
kakashi just needs to take distance from it and attack hashirama from long range with kamui