I say the fewer middlemen, the better. With an ECN, you have 3 parties: 1) buyer 2) seller 3) ECN collecting a small fee. On the NYSE you have 4 parties: 1) buyer 2) seller 3) NYSE collecting a small fee 4) specialist trying to screw the buyer or seller wherever he can to make some money. Usually, it's best to send your order to the place that trades the most volume in the security that you are trading regardless of if the market is open outcry, electronic or hybrid. But electronic markets have grown a lot in the past 10 years and will continue to take market share away from open outcry unless the open outcry markets are given a monopoly. Look at the electronically traded ES futures on Globex vs the pit traded SP futures. The dollar volume of the ES is much larger than that of the SP. But yet, the powers that be continue to only allow pit trading for SP during RTH. I think open outcry markets' days are numbered.