You figured out what I meant exactly, good job. The way I tell which method I should calculate is by looking at the history and see if it bounces off the lines. Generally you'll see some big long run, and then a bounce *to the pip* off the line on the ECN. Broker data gets a little fuzzier and it is usually within 3 pips. If you see that happen a few times in the past day or so, it is a good indication you got the right settings.

I tried to write an automatic way of switching/detecting the settings and I simply failed. The code method was about 30-35% accurate, the human method was about 85-95% accurate.