In regards to API trading, it seems that IB has priced their order execution structure to almost force everyone to use smart routing, which includes Timber Hill, their market making operation as a liquidity provider, for example, using their flat rate commission structure for US shares is $0.005 per share, however if you route direct to an exchange and don't use smart routing (taking out the option of a fill with their market maker) they ask that you pay $0.013 (almost triple the fee) and they don't even allow you to use direct routing on their cost plus pricing structure, in other words they penalize you heavily for not giving them the option of filling your order in their book, whether this is ethical or not is another question, however are their other brokers out there that are truly non-bias to where you route? and don't want to penalize you if you don't fill their own order books?