From what I understand the key difference is that live() keeps an eye open for new DOM elements that match the selector you are working on, whereas click() (or bind('click')) attach the event hook and are finished.
Given that alot of your code is loaded asynchronously, using live() will make your life alot easier. If you don't know exactly the code you are loading but you do know what kind of elements you will be listening to, then using this function makes perfect sense.
In terms of performance gains, one alternative to using live() would be to implement an AJAX callback function to re-bind the event hooks.
var ajaxCallback = function(){
$('*').unbind('click');
$('.something').bind('click', someFunction);
$('.somethingElse').bind('click', someOtherFunction);
}
You will need to keep proper track of your event hooks and make sure this function is rebinding the proper events.
p.s. Ajax methods .get(), .post(), .load() and .ajax() all let you specify a callback function.