I think it's fair to say that 2 strands of 60 do not have the abrasion resistance as one of 120. The reason twisties are popular is because they simplify and slim down rigs for casting. Okubo in Legends Five is tying his bimini to 170lb braid with a simple system. It is the start of a Fisherman knot in the leader and finished with a uni knot in the braid instead of the jam used in the traditional fisherman. Obviously if you watch Okubo this method works fine!!
All the japanese anglers that I have talked to basically use whatever Konishi, Okubo or Suzuki use, ergo not a twisty.
I like Okubo's shock leader system it's so simple, who could be bothered tying something like 200 to 400lb leader together when a crimp will do such a good quick and easy job. Start off with a twisty and crimp the appropriate shock leader on the end, it works a treat.
As far as Okubo's twisting and doubling back the leader and crimping on the popper goes you would need to not be a constant lure changer or have a quiver of rods to use this system. If you watch all the legends they don't use swivels and split rings much at all and the only reason we can come up with to explain this is that a ring and swivel in front of the popper will break the water before the popper bloops therefore reducing the intensity of sound generated. Me, well I do like the option of quick changes so for the time being i'll stick to split rings and swivels or solid rings.