I don't know of any 3pp rules, but why not use the mystic as it is currently presented? You could even give every character a psionic talent, for fun, make them roll on a table to choose their talent randomly.
Agree with above. Try out the stuff that's in testing.Honestly my only complaint is it is a LOT to read for one class (since it basically is method of performing the functions of every other class). And still needs some general editing done. (Darkness has no duration, so logically its an instantaneous effect for psions, and they can eventually cover the earth in magical darkness!)
I think I am going to try to pester my DM to allow it to MC into since we are in middle of campaign. (While at the same time telling him he really shouldn't because its kinda crazy powerful if allowed to multiclass)