There used to be a problem with Powerbook keyboards that they couldn't register more than 2 keys pressed simultaneously (plus modifier keys). I don't know if this affects the current generation but it might affect your play of EVO - pressing Z for afterburners, A for autopilot to keep locked on, space to fire and R to retarget is a pretty common occurrence... you might want to check.
Nonetheless, I wouldn't think any of this should affect your decision to buy an iBook - they are cool and, great as it is, EVO is still just a game.
Its amazing how "tsk, tsik, nik" can mean anything from "There's a bomb in the bus, get help!" to "I'm hungry, feed me"
In case of ambiguity about anything I say - choose the nicest interpretation.