Ab-Roll-Exercise

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So I recently tried an ab-roll. Now I want to implement this exercise using a barbell.
Now my question:
-Just the barbell
-The barbell with weights

Do the weights even offer enough resistance when you go back (since you roll)? Is the increased range of motion worth it, using just the bar?

And how does /fit train their core?
I personally favor the compound exercises, farmers walks and cable crunches.