The only good reason I've seen to have client side navigation is when there's a permanent sound player embedded in the page, so you can keep listening while you

The only good reason I've seen to have client side navigation is when there's a permanent sound player embedded in the page, so you can keep listening while you browse around the site (possibly for other things to listen to). Although really, for longer-term listening, playing the stream in a separate media player is a better idea. But sites tend to hide their stream addresses, and this is also usable.