I prefer wax potting over epoxy potting because you can repair a broken pickup when potted in wax and usually throw away the one that is epoxied. You can repair epoxied pickups in some cases but they are difficult to take apart and the chemicals needed to remove the epoxy will usually eat away at components such as plastic bobbins or covers. Another downfall of potting with epoxy is the solution take time to dry and usually dry from the outside first leaving the inside still liquid. In time the epoxy inside could seep out into the cavity or make a mess inside the instrument. Epoxy is known to shrink and if the solution is in contact with the bare magnet wire there is a chance the wire can break. As the epoxy shrinks, it can pull the fine magnet wire or connections and can cause the pickup to stop working. I’ve seen this happen often especially when instruments are in hot and cold environments.