re: What stop-limit do ya'll typically use?

Stop limits at opening bell are hugely dangerous especially on securities where mm's control the spread. The real inside, not the hidden inside, which isn't always easy to determine. You would be better off using some sort of hidden order, but only after checking level two, and attempting to route the trade for more security. Route it directly to someone who has a large block at the ask.

If you trade/invest on IB, I'd route it to a dark pool. Or tow a platform that rebates commission. A liquidity adder.