That is a bad idea.
Especially since you forgot to tell the poor guy that if he does that, he'll have to put in an ob_end_flush.
Personally, I wish they hadn't added that feature to the php.ini, since ob is still very new and seems to have some issues.
in the script that you want that to happen in, you can start your output buffering like so:
<?
ob_start()
//do a bunch of stuff//
//set ALL your headers...
//and pipe them out to the browser
flush();
// do some more stuff...
//and exit...
ob_end_flush();
?>