When using amfphp or flash remoting for that matter, you'll find out that you Actionscript code understands your AMFPHP objects and vice versa. No need to parse data into native Actionscript objects. Agreed, E4X etc has made this less harsh to use, but you'll still gain a lot on the client side of things.
AMF compresses data very strongly and is a much faster ( = better ) way to communicate from your app server to your application. BTW, there is a lot of good documentation on AMFPHP. Check out the blog from the creator of AMFPHP, Patrick Mineault<http://www.5etdemi.com/blog/> .
