Let's talk SWF filesize for a moment. My current situation is that I'm building a Flash / HTML hybrid website and minimal filesize is still the name of the game for SWFs. On the page at hand I have 2 SWFs that talk to each other with ExternalInterface callbacks and fetch content using AJAX that loads bits into the page as well as the SWFs. 

I recently had a Flash / AIR project that required the ability to render PDFs. Evidently, this hasn't been a hot issue in the past for Flash applications, however I get the feeling that AIR may change that. While a web application can utilize any of many server side solutions to render a PDF to the browser, it's not the same for AIR.