Question 1: “should i only Trade the new ones or is it a Great tactic to test around, Write them down and use the best of all the Versions?”
Answer 1: Petko recommends trading the TOP 1 to TOP 3 Expert Advisors. Since you are testing both V5.0 and V5.1 you could combine V5.0 and V5.1 and trade just the TOP 1 EA or the TOP 3. There is no right or wrong method.
Question 2: “how do you decide if an ea is the “Top Performer“ and how Long it is one?”
Answer 2: To determine top performers use only the closed trades. I personally use FXblue to sort the performance of all the EAs from top performers to bottom performers. From this sorting it is easy to pick the top performers. To determine how long an EA will remain the top performer I check FXblue every few days to see if the top performers have changed. As long as the EA I am trading remains in the top performer position when sorting the EAs I continue to trade it. Once it falls out of the top performance position I stop trading it and start trading the new top performer.
I hope this answers your questions. If not, then please let me know what I am not explaining. I am here to help!
Alan,