direct drive has the advantage of simplicity, less to go wrong, but the potential for fragility when the drum stalls out.

using an o-ring and a pulley for a simple belt system has the advantage of helping protect the motor and esc from damage when it spins, alongside greater design freedom as to the size and location of the drum and motor, but at the risks created by the potential for the belt or pulleys deforming or snapping under load, or other issues that can occur as a result of belt-tensioning.