The point is that the cheap swivels do not rotate under load. Maybe they do when they are brand new but they surely don’t once they are worn in. However, they may turn well, even when old, if the swivel is rigidly connected to the drum as is done by reefing systems. The dynamics of reefing systems is different from furling systems and should not be compared. Depending on your average load, frequency of use and sailing area, I would recommend the Harken “high load” version or the Bartels drum and swivel for furling. These parts are designed to turn well under (heavy) load. I am sure there are other drum/swivel brands with similar properties, it is just that I have not seen them yet. Keep in mind that a Wayfarer is sailed with a pretty high rig tension compared to some other similar sized boats.
The reason I switched from a furling system to a reefing system is that I sail the river Meuse a lot. This river has big, old oak trees lining its shores. These trees cause severe gusts when passing them. The gusts are often that strong they cause the sail to unroll and twist. After two or three trees I end up with a ball of cloth on top of the drum and the rest of the sail flapping freely about. Because of this effect (caused by the sailing area) I never want a furling system again. With a reefing system this cannot happen because the swivel is rigidly connected to the drum. In other words, a reefing system is superior to a furling system, even when it is never used to reef a Genoa.
One more thing; the usual 150 – 160 kg load is the pre-bend load. It is not the actual load while sailing. The sails (kicker, sheet, cunningham and halyard tension) add tension to the rig and it varies a lot. Also think about what waves and gusts do to the rig tension! (Not to mention that uncontrolled jibe, the other day). Peak loads may be closer to a Ton then you might think (pun intended).