For example, this might reduce (though not eliminate) a PCs ability to mess with other PCs during the exchange of chyen. Due how to things work in the game world I could see this as being safer than most bank transfers.
I also worry that the 'me in we' can get lost a little if it becomes too easy to unify a character's resources. Again, it's not absolute and the impact this would have might be bad or good.
I guess that this is just one of those changes that, while seeming so simple on the suffice, could have a greater impact on the game than one might thing and should therefore be seriously considered.
Suggestions:
1. Require a high minimum balance (~50-100k), to provide high risk for using this as a transfer service.
2. Make data on joint accounts easily available to decker types, to ensure any attempt at using it as a transfer service is less secure than other methods.