This is a very extensive guide and I appreciate it.
There is one point I want to make and not sure you mentioned it.
One of the other reasons why other people wants to be powerleveled is for PVP. They want to be L50 fast so they can start their PVP toon and customize the powers suited for PVP. I know there are PVP addicts out there that don't care about PVE. I read this somewhere but not exactly sure where.
For other games like WOW, they say Life Begins at Level 60.