I used to trade listed, and now plan to start trading nasdaq and ETF (AMEX). Suppose ARCA, BRUT, ISLAND all have the same offers, and if I like to join the offer, where should I route my limit order? Should I join the one with the largest size or smallest? Do they give you the same rebate? Do they offer rebate for ETF such as SPY, DIA and QQQQ?
Your broker SHOULD have the ECN fees/rebates posted on the site or readily available for you to view. If not.... call them up and ask.