Of course. IBKR has lower rates and approves more easily, therefore they will be much more trigger happy. CS timidly emailed about potentially discussing margin rate adjustments, IBKR can liquidate your positions for instantaneous margin violations without warning or a margin call. The assumption is your leveraged position is hedged well enough to protect against untimely margin calls, and the cost of hedging is roughly equivalent to the nominal margin rate savings they offer.