Hi,Husk,
I've been trading QID/QLD in 500 block with Schwab. I've try market,limit order,and stop limit. Market order usually get filled quickly but the price is very bad, as much as 0.5% slippage. Limit order get filled reasonably fast, usually 100 shares at a time. Buy/sell Stop are tricky, and I've seen price went thru' the stop without a fill, then eventually filled at a bad price. Hope this help. Alfred