I think the current weak stone is already very confusing, judging by my experience and some other comments, but I have not done any real playtesting.
But I would argue that first time players shouldn't play with the pie rule: they should just get the first-player advantage. It's a nice way to handicap the AI while the player learns the rules -- by the time someone knows the game well enough to play the balanced version, they have to learn a new rule. Just like new Go players start with extra stones on the board -- the game is the most fun when the two players are equally balanced, not necessarily on equal footing.
I think there's an implementation that makes it pretty intuitive: the first stone played doesn't get a border (or a more clear visual indicator that it's not capturable :). So the second player can choose to capture it, or to play elsewhere. If they play elsewhere, the first stone then becomes "locked." I think that's clearer than like switching colors or something.
The strategy for first-move play seems easier to grok than the strategy for a 55% weak stone, but I have to caveat that with: I play Hex, so it's familiar to me.