For backtesting on low Timeframes like M1 it would be more realistic if we could avoid the data interpolation issue that exists at the standard MT4 Platform.
Also not having the variable spread like in live trading is not so realistic as it could.
And where most of us are familiar with is the problem of being dependend on the last available live spread when backtesting , especially in the weekends where the last recorded "live" spread from friday is so wide that low timeframe backtesting during the weekend is useless.
Also the data quality derived while downloading directly from the MT4 Platform is discutable.
Some time ago i found a website that describes a complete and free method that all these issues solves at once.
There is some work to be done to get all work together but perhaps we can share our experiences here and help each other.
MT4 Tick data | Birt's EA review