The best practice is to have equal (or almost equal) backtest in MT and in FSB Pro. Then it is preferred to trade with exported Expert Advisors.

We developed and used FSB Pro - MT4 bridge before making possible to export Expert Advisors. Then we rewrote the FSB Pro calculation engine in MQL and include it in every EA produce by FSB Pro. Basically we have to achieve equal performance in both ways of trading but it is possible to have difference sometimes.

The benefit of using the FSB Pro bridge is that we have one and the same engine for calculating the backtest and the trading signals and equal indicators code. The drawback is that the communication between FSB Pro and MT can be disturbed by other processes that work on your computer. For best results, you have to use a separate machine for trading. We use the FSB Pro bridge for strategies that use custom indicators without MQL versions.

The exported Expert Advisors include a calculation engine, execution code and indicators code. The benefit of teh exported Expert Advisors is that only one platform ( MT ) is required to run. A discrepancy is possible only when there is an operational difference between the MQL code and the C# code used in FSB Pro. For that reason we recommend every EA to be backtested in MT before running to trade. Despite the imperfections of the MT backtester, it is necessary to run our experts simply to be sure they work in MT and there are no obvious bugs.

You should not trade Expert Advisors that don't run in the MT backtester. Most commonly this is a signal for a potential bug in the indicator or in the EA code.