Without going into too much detail, the reason I’m beginning to head in this direction is that JQuery is supported by Microsoft now, so I get to learn it, standardise on it and use it across multiple projects.
When I need a more extensive RAD environment I can plug in ExtJS over the top.
ASP.Net Web forms are often too ‘heavy’ so I can move to the MVC framework for Test Driven Development, and a lighter weight server side model, but might not be able to do this immediately (client requirements for non beta stuff etc). By abstracting all the data / logic into model / service layers, I can create http handlers for AJAX requests that spit out JSON and call the respective layers directly for stand web requests.
Using LINQ to do this proved an absolute dream. Serializing objects returned from LINQ, to JSON, spitting the data back via http handlers and then consuming them with ExtJS meant I could achieve some really polished results very quickly.
Hopefully I’ll add some code to support all myc ranting soon,