It seems to me that the black player who chooses the setup has an advantage to his white opponent who doesn't know what will be the setup. It is true that the black player may know an opening theory for his favorite setup but as they are a lot of possible setups, one would have to know a lot of opening theories which is reducing the impact in my opinion.
There is no game-theoretical advantage from choosing btween a number of symmetric, and therefore mostly equivalent start position. The only way black can derive any advantage from this is by having very extensive opening knowledge for the setup he is going to choose. Only white would have to prepare for all openings, if he has no clue what black is going to choose. (Which presumably is hopeless, due to the large number.) Black, however, only has to prepare for one, and can use that one in every game he plays as black. (And even if it is commonly known what he will pick, it is not much help to the white player if he has to play a variety of opponents.)
So I think that rather than doing away with the burden of opening theory, your rules compell the players to study opening theory for black, in order to neutralize the first-move advantage.
There is no game-theoretical advantage from choosing btween a number of symmetric, and therefore mostly equivalent start position. The only way black can derive any advantage from this is by having very extensive opening knowledge for the setup he is going to choose. Only white would have to prepare for all openings, if he has no clue what black is going to choose. (Which presumably is hopeless, due to the large number.) Black, however, only has to prepare for one, and can use that one in every game he plays as black. (And even if it is commonly known what he will pick, it is not much help to the white player if he has to play a variety of opponents.)
So I think that rather than doing away with the burden of opening theory, your rules compell the players to study opening theory for black, in order to neutralize the first-move advantage.