I have never had the privledge of attempting to open a 50 lot order before.... 25 for that issue.

If you're trading with an ECN, at what point do you begin noticing delays on your fills? I supposed you could chunk the orders to smaller dimensions (say, 10 5 lot orders) but could anyone share their experiences with if their lot sizes were too big to get packed instantly?

My guess is that our scalpers (fxRichard, currencytrader, linuxtroll, etc) can shed light on the subject.