Have a Look at the DAX from 16th October from three brokers. Highlighted a few loions.

FxPro cTrader


ICMarkets MetaTrader 4


FXCM Trading Station


We are talking at least 50 pips difference. Also, https://www.reddit.com/r/IAmA/commen...est_retail_fx/ might be an interesting read.
. . .25% of the time that I had been trading the firm's money, while 75 percent of the time that I had been tasked with figuring out which customers we could bet against and which customers we should target to attempt to reverse engineer their own egies.... Do not know how reliable this is, but nevertheless interesting.