@Jeffro

I use plugins such as Exec-PHP on some of my sites so I can easily to execute PHP in the body of a post or page. Exec-PHP uses the Eval function. This plugin has been very useful in the past in order for me write PHP code directly in the post/page to 'hook' into 3rd party membership scripts and show content in the post depending on the user logged in status.

I have also used a similar method to access api's of web services direct from within posts/pages such as videos stored on a content server. This requires you to 'talk' to the video content server using PHP and their provided api's to load in video play-lists. The only viable way I found of doing this (for me anyway) is to be able to execute PHP in the body of posts/pages using functions such as Eval (so I can load in post specific video content).

As for Eval security/performance I am by no means an expert in the deeper workings of PHP but have sure found functions such as Eval useful. In the future I think a lot of the functionality of what I need to do could be parsed out to short code functions - but there may well always be a need to execute PHP code from within a post/page. I am not sure yet if there a situation where PHP in the body of a post/page could not be handled by using short codes (with attributes) instead.

David