Psion
Adventurer
Heretic Apostate said:So... What are the downsides of these classes?!?!
They aren't as powerful as they appear at first glance, because they require a lack of focus to get into.
That said, IMHO, they are still too useful, too flavorless, and the entry requirement for Eldritch Knight is a joke. The Mystic Theurge is okay at low levels but the double level bonus catches up and makes it too useful at higher levels.
I have done some conversion work to give them more flavor and make them more balanced, in the form of more class abilities (including that much vaunted ASF reduction) and fewer spellcasting levels. These classes have a philosophy of giving 90% of each contributing class abilities; I think 75% of each would be more appropriate.
They make good starting points for your own classes, but taken as is, I really do not like them.