yep always best to make your own :-)

What a top mounted roll of filament does is massively reduce the tension on the filament. At the side the filamen has to go up and then a sharp bend down to the extruder. Putting a lot of unnecessary strain on the motor. With it on top of the frame, it's a shorter and smoother pull - so you can print faster and reduces motor skipping.
This will also help immensely if you use flexible filament.

With the 2020 extrusion it's really easy to bolt stuff to the frame :-)