If you use the MetaStock Enhanced System Tester (EST) in the development of your trading system, it is important to verify the results. Some configurations, for instance, may result in simulated trades that you would never execute. The EST may both buy and sell a stock at the same time. That results in two additional brokerage fees with no possibility of profit.
The pitfalls in the use of the Enhanced System Tester have been documented and it is wise to be familiar with the available cautionary publications. Foremost is Sprunger's Guide to the Enhanced System Tester.
There can be calculation differences between them but if you plug investment rules created by GSSTA into the MetaStock System Tester, you should see agreement in equity and profit values. The differences will amount to less than one-half of one percent.