you have to wonder if the beta tag has been applied purely because of scaling the servers, artificially holding back to the 4S rather than iphone 4 and ipad 2 probably makes capacity planning a lot easier!
I can tell you this, last night while playing with Siri we had several periods where it "couldn't connect to the network" - these were not networking issues, everything else worked fine.
By "not networking issues" you must mean not issues with your network: because surely they were networking issues related to Apple's AI processing network... i.e. the cloud