I emailed someone from IB and the person told me IB cannot reveal what the SMART router does due fears that the competition will copy them. So there is no way to know if SMART has a Thor like system. I suspect it does, I'd be shocked if it doesnt
I'm fairly confident that SMART simply routes the order to a single venue based on the best choice at that time, as opposed to the Thor model of breaking up the order and hitting many venues in parallel to get as much volume as possible before others can change their resting orders.
FWIW, I've changed from the default SMART to the SMART Primary (which is biased towards routing to the primary listing exchange, typically NYSE for me) and have seen better fills. Strangely, I still see many orders cleared on non listing exchanges (like ISLAND or CSFB or CITADEL) which some rep tried to explain to me with mumbo jumbo, but I'm fairly certain that SMART's mechanics was even more of a mystery to him than to me.
YMMV, of course, depending on your order types and aggressiveness, instruments, order size etc... PM me if anyone is interested in details or benchmarking.
