This looks cool. One question: how do you deal with split transactions? The comments in models.py suggest that they are supported. However, the signature of the debit and credit methods in AccountBase only have space for one account on the other side of the transaction, e.g.:

def debit(self, amount, credit_account, description, debit_memo="", credit_memo="", datetime=None):

Are you planning to implement it later, or did I miss it in my quick reading of the code?