I have two very basic spot FX data questions. I trade FX futures and have never spot FX before. Question 1: How do I know that my data provider's quotes are the same as my broker's quotes? Or, at least that they're nearly the same? For example, I've done backtesting using both Barclays and Tullet spot FX "tick" data and I like both feeds but I'd like to keep my account at a multi-asset broker such as Interactive Brokers. Can I do this w/o getting killed on execution or is my idea foolish? Do smaller traders get their live FX spot data from one source but trade w/a separate broker? Question 2: Does anyone know where I can get Barclays or Tullet historical data? Is there a reseller out there or will these companies sell their historical data to non-brokerage customers? The Barclays and Tullet historical data that I've collected so far has been gathered in real-time through IQFeed which is a real-time data provider only.