Not sure if I'm right in thinking this, but if you have the Open Price, and the Close Price, and what MetaTrader reports to you as the Pip Profit / Profit, then isn't it possible to calculate the Spread that the broker then uses per Symbol and the time?

If this is true, then not only can it give you good feedback on the Spreads in effect vs the volumes of trades closed etc per account, but also across all users showing the average broker spread etc.