The only benefit that DAMO is a non-technical one - that existing Outlook end-users do not have to go through another learning curve for learning how to use the Lotus Notes clients. Any product that goes through a middleware has its technical limitations - one thing for sure, some of the Notes clients features may not be fulfilled in Outlook.
See the list of problems presented LIVE to you in the Domino discusssion forum (search key = "DAMO"):-
Notes/Domino 6 and 7 Forum : Search Results
Theoretically, if there is any limitations when processing messages sent from Outlook, then BlackBerry Enterprise Server may encounter similar issue too. So be prepared to see some abnormalities.
You can see the list of beautifully described advantages here:-
IBM software to access Lotus Domino from Microsoft Outlook