Mike805, Have you looked at the slippage from sending stop orders to the exchanges for listed stocks?
I don't recommend sending stops to NYSE. They seem to only trigger on NYSE prints rather than consolidated prints. I have much better results with stop orders that are held by my broker.
Not sure if this answers your question direcrtly but, a few years ago I was using a different platform where I was routing to NITE and NYSE frequently. As you maybe be aware, NITE was (a likely still is) one of the worst offenders with respect to slippage and held orders. They really utilize that order hold capability in what they claim are "fast markets". Total BS IMO. I actually had one order held for over 30 minutes that cost me quite a bit (I think the fill was about $1.50-$1.60 away from my stop almost 30 mins after the stop order triggered). I couldn't cancel or re-route due to the shares being held, i.e. held by NITE. I called my broker, and after a few days of arguing and BS, they broke the trade and gave me a better fill price. I stopped using NITE after that... NYSE was a similar story. I use MOO orders quite a bit and was told to try NYSE. I got fills that were much worse than ARCA - sometimes so much worse that I stopped using NYSE about a week after I tried them. Thinking about it now, electronic liquidity is the only way to go IMO. It makes sense, orders are prioritized fairly every time and there is no contention with the middle man. Just my 2 cents. Its been a while (3-4 years since I used NITE and NYSE) and things may have changed. My broker/platform at the time may have had something to do with it too. Mike