One of the first things that grabbed me about PHP was not that there seemed to be a way to do everything I wanted but that there were often several ways of doing it, I think this is the case here, most non PHP'ers could guess what <?=$str;?> meant in a second or so.
But I think the whole point here is for non-coders, i.e. designers who want to include pre-written features, I have just written a few forms for a client and all the client has to do is insert
or whatever - wherever he wants it to appear in his page.
<? echo ("$client_application_form");?>
<? echo $client_application_form;?>
+ printr() & surreal combos of include & readfile & implode(,file())etc etc all work, but for a non-programmer
the first causes less confusion, ok its hard to get <? echo $this;?> wrong but they do !
also its less typing so I use it wherever I can