Hi,

You can definitely have a single Data Adapter for both the kind of subscriptions, as streaming and polling modes are handled by the Server directly. But in most cases the user cannot perceive any difference between streaming and polling, due to the highly optimized polling mechanism implemented by Lightstreamer. So I guess that by "polling" you mean something else, where the user can see a real difference in the quality of service.
Can you please expand on your requirements?