For data loading, yes. But here's a few random thoughts:
* I can pre-emptively load data in a SPA (think: 3 screens-worth of a datagrid) and keep fetching in advance, so the user rarely feels the lag.
* Much of my investigation has been around adaptive forms, wizards, validation and keeping logic in a single place. Having to define models and logic once, rather than client-side and server-side would save so much time.
My testing suggested that client-side validation still gave better results, because it was instant. Moving forward & back through a wizard was better if client-side rather than each screen rendered server-side.
I experimented early May so am a little hazy on details (and can't find which PIM I put my notes in, sigh) and look forward to seeing other people's experiments. Particularly when not run on their local machine.
In some cases yes, but I don't think you can get away with client side validation for a lot of things because they depend on the state of your database to return the correct result.
For example, how would you validate an email or username on the client when the availability of the name depends on you making a database call to see if a user exists already? You have to make a network call, get the result and then update your validation errors on the client based on that server side result.
But for validating something like a phone number or twitter handle, sure, client side works all the way but I don't think having even 200ms of delay for that validation is going to make for a bad user experience. 200ms is a lot too. That's about what it takes to ping a server in Tokyo from New York.
Your other points are valid tho. I guess we'll see where LiveView ends up going.