That works awesome if you're on CS4/5, but there's apparently still no solution for CS6 and on? I mean, how has this not been added as a native feature of the program yet? Even just to be able to open the same PDF file as two separate documents instead of opening the same page twice.
Just a quick note here: Illustrator is NOT a PDF editor. You can do some serious damage to a PDF that was not created in Illustrator.
Editing a PDF in Acrobat Pro DC is easy to do and works great unless you're missing fonts.
Here's a video tutorial about editing PDFs in Acrobat DC: http://www.jeffwitchel.net/2015/08/edit-pdfs-like-never-before-in-acrobat-dc/