The first time through, I deliberately avoided reading any strategy guides, and lost Bastila with a really excellent 2-handed lightsword, which of course she promptly turned on me when we met, again.
Similarly, I'm curious what changes there would be if you reached the exp cap before hitting the Leviathan--whether Bastila would have a different selection of powers after she rejoined you. Presumably, she wouldn't, but then, Malak also manages to penetrate even the best force resistance powers you can have up in your first battle; so we know the game cheats.