Eventually I plan on going back and reading what others have posted here, it is late and I am too tired to read such a lengthy discussion. However, I did want to toss in my two cents.
What do psionics mean to me? Telepathy, telekinesis, mind control, mental attacks, the ability to affect the environment using the power of the mind. Honestly, if magic can do it then psionics probably can too.
I have tried psionics in 1st andd 2nd edition AD&D and while I thought it was a neat concept I always ended up steering away from them. The reason for that is simple, it was a whole new mechanic thrown into the game that was not needed and made it more complicated. More for me to learn and more for my players to learn.
The first and only time I saw a psionics system I liked was in Monte Cook's Arcana Unearthed/Evolved. The system for psionics was the magic system, spells were just given a psionic template. It worked smoothly, was easy to learn and did not require a whole new system different from the rest of the game. I would not want to see concepts similar to laden spells and templates introduced to make it work because those things do not exist in the magic system Pathfinder currently has (they were great for Monte's game because the whole magic system used them). Psions would have their own "spell" list, and it should include spells that currently exist (much like the overlap that we currently have with arcane and divine casters having some spells in common) and some spells unique to their class.
To sum up... Make psionics work like the magic system and I will buy it and probably use it.