DevForce itself doesn't have any requirements for browser vs. client stack, and except with the Push feature, we haven't seen any problems with the browser stack. If only the client stack is working for you, and you're not using ASP.NET security, there shouldn't be any problems with using it.
Curious, though, that the browser stack doesn't work. What browser are you using?
The "no endpoint" error can unfortunately mask many connection-related failures. Is your client application able to connect or login, or does it fail with any attempt to reach the server? The inner exception(s) can sometimes help trap the problem, as well as the server's debug log if any server code is throwing an exception.