AJAX, Thick or Thin client

There’s an interesting blog post discussing the pros and cons of rendering a page on the server or client side. The main point was that by using a technology such as JSON to only transfer the data necessary for the page to the client and keeping all display logic in javascript(Thick Client) you reduce data transfer requirements. The greater the amount of data that needs to be transferred the more sluggish the app will feel.
An area that I’ve been working with and have seen mentioned over at Ajaxian is to use a Thin Client approach (logic on the server side), but then use hidden divs and use local javascript to manipulate the divs. You take a slightly higher hit up front for page load as extra non-visible data is passed to the client, but later interaction time is reduced as further communication isn’t necessary. This also simplifies app development by leaving the logic on the server. Not only is the development of a full MVC environment difficult in javascript, but you open yourself up much more to browser incompatabilities.