cTrader Algo Backtesting

Dear cTrader,

I am backtesting my cbot on Spotware demo account, then I tried the same with zero changes on a broker demo account and I am getting different results.

What do you reccomend to backtest, is Spotware demo accont reliable for backtesting? I am using tick data from server (accurate).

As I am planning extensive backtesting, before to start I would like to know your best practice, what account I can trust and your reccomendations.

Also, as cloud  spot instances can be very cost-effective for this type of workload, is cTrader Backtesting  fault-tolerant? If for example a VM is interrupted, can I resume the backtest or it is lost? 

Thanks in advance for any info you can provide and for your support.