Chris commented:

“Wouldn’t 行ったみたい rank somewhere between 行ったって and 行ったそうですin terms of politeness?”

And I replied:

“I don’t want to write too much about this here because I’ve been planning on writing a big post about らしい, みたい, よう and そう – these are hard to get sorted, and I’ve decided to take care of it once and for all.

みたい implies more of a guess on the speaker’s part and less direct reporting. It’s definitely somewhere between the two in terms of politeness.”

Ingve said:

「But what about 行ったって　? That should make it clear that “she said she went”, whereas 行ったそうです　is closer to “I heard that she went” or “apparently she went”.」

And I replied:

「This is definitely true. って is far more commonly used to express the fact that someone said something, but I’m not sure if there’s a polite alternative to it besides 〜そうです, so in some cases, the polite cases, it could be translated either way perhaps?

行ったって is sooo nice and efficient, by the way.」