Performance and scaling? I don't know that there's s huge difference between the two architectures. In a multi-system landscape, obviously the central system had a little more work to do. All it does, though, is serve the flavour definitions - the screen re-writing and script executing happens in the browser. I don't know of anyone that has configured their system this way, but I really wouldn't expect a big difference.
Yes, I'll be in Berlin next week. I should be hanging around many of the Personas sessions - feel free to say hello!
Steve.