Hi MrPrice,
I see a few main issue with your comparison.
1 – You are using the inherent JFD data in EA studio to compare with your broker terminal data. You should first use the export data script to export your data from mt4 into EA studio for a fair comparison. Additionally this will automatically match all swap values and allow you to set commission. But note that MT4 doesnt include commision and so for a pure comparison its better make this zero and then change it afterwards.
2 – You are running the MT4 backtest using ticks instead of open prices, it is best to use open price modelling in the MT4 backtester.
As to how reliable is EA Studio, very. Experiences like this are always user error.
I would strongly recommend reading the thread below in which I helped someone with similar issues.