Russian oc is alot more international and widespread. There not as organised as the mafia, but i dont think that the mafia structure of family is something that would really work for them.
And also i dont think that the russians would really need to displace the italians to be successful. http://www.bunker8.pwp.blueyonder.co.uk/orgcrim/3802.htm

Heres a few interesting articles on gang structures.