[romaniv]

This does take explicit coding. But, if fragments of the page are being replaced as bcx does, then you need to do similar coding anyhow.

It should not be similar. There is a huge architectural difference between the two approaches. In server-side approach you're adding caching or prefetch to an already working application that has established and working URLs. With client-side approach, you need to implement adapters that transform URL information into the client state that is normally achieved by a series of UI operations and AJAX calls. Then you need to add new code to generate URLs and manipulate history.

The beauty of caching or partial page fetches is that they are generic. History manipulation is not.

js works pretty well on modest smartphones, at which level network latency is usually the major concern...

The last time I tried to browse on Kindle, it choked and died on most JS heavy websites. When 500MHz processor is not fast enough to browse the web, to me, that's a problem.