What is the benefit of Panels Everywhere
My experience with PE (panels everywhere) was great.
I been working for 1 year with PE on a big project and i can say:


The first advantage of PE is the entire layout control. while panels only affect the "content" region, PE get full control of all page including header and footer (which is no possible only with panels).
Second big advantage its the possibility to select variants as layouts letting you decide wich layout (variant) to show on every page taking that decision with the access arguments like a normal panel.


as you can see there are similarities with Omega theme, and in the fact both modules resolves the same issue.