Then please write a decoder which is designed to be used that way! As I stated previously, the LCIO one will not work. I tried it and it does not correctly work when going to the next event.
Also, as you said, this would break (the currently not required) thread safety. While probably this will not be an issue in the near future, I don't like introducing such hindering constructs for eventual future features. Even worse when it's a dirty hack.