A word of caution: it's not the ADP per se that make it works with 1000 users.
It's how you design the application. I'm reasonably sure that a MDB would be just as capable, provided it's designed correctly.
Another thing we need to be careful is to not conflate what belongs to server and what belongs to client. For instance, number of connections that is possible is a question only a server can answer. It doesn't actually matter what kind of client you have, only the matter of connecting. If we change the question from number of connections to how many concurrent requests a server can handle, it now can only be answered by clients, not the server because it now depend on how nicely the client plays with other and doesn't try to hog the server for all itself.