Not to mention that during events like the flash crash of 2010, even small volume traders with stop losses got screwed. A stop-limit order in some cases works

Not to mention that during events like the flash crash of 2010, even small volume traders with stop losses got screwed. A stop-limit order in some cases works better than a stop loss order, but if there's a rapid crash that's not going to bounce back, a stop-limit order will be worse. There's really no substitute for robust alerting for abnormal market conditions and getting eyeballs on the problem quickly. (I was writing execution algos for a Fortune 500 broker dealer during the 2010 flash crash.) (This is not trading advice. Don't mistake it for trading advice.)