Hey Tai,
Glad to hear from you.
I think you are doing the very right thing!
The thing with Dukasckpy is that they guarantee that they have the same data on Demo and Live. This is why we selected them to use their data for the Free Historical data. However, I am still testing it and so far so good. And I think many of our students are testing as well and for the moment no one reported that the data is different.
I have been using JFD a lot and the results from Demo to live are nearly the same.
Pepperstone I use just for crypto trading because they have good spreads for those.
I hope that this gives you a better idea.
Cheers,