Has anyone been banned using ISBoxer?

[Wubsie]

No. No one has been banned for just multiboxing with either HKN or ISBoxer as that is not a bannable offense. There have been false positives for botting where some GM doesn't know what they're looking at and some people have receives bans for more or less unattended gameplay (Mirai had a good video on the subject:https://m.youtube.com/watch?v=99EhfRWYANA), but even a in those cases the bans have commonly been overturned.

So: both are fine, just don't try to game the system.