Thanks for the references. I can see there that there is some sentiment there for M=1000, MM=1000000. However, none of these seems to rise to the level of an accredited international standards organization - such as the American National Standards Institute, British Institute of Standards, [International Standards Organization], or similar - each of which have standardized the use of SI prefixes. Further, your bankersonline reference seems to indicate that the traditional financial prefixes may be an anachronism on its way to disuse.
However, tradition is a strong force. I'll leave the bankers to their traditional units. I just worry the potential of magnitude errors as these two systems clash. Indeed the bankersonline link you provided already alludes to such a problem.
To those not interested, sorry for the sidebar. I'll drop this line of inquiry.