I don't know about this one. I'm old school but I'm not that old school. Reintroducing soldering/crimping to residential would present all sorts of problems as most people who wire houses today have no idea how to apply either safely to solid conductors> Most of the old solder kings have passed on.Most young ropers have no idea what a c24 is, (though it is still used and even required for crimping egcs in some locales) let alone how to use it correctly and the youngest of the men who lugged that tool and used it regularly to squeeze copper barrels around twisted solid cccs in the '50s and '60s are now collecting medicare. Many guys wouldn't even bother to purchase this tool anyway due to $$ and would end up using the crimp punch on their linemans-causing a bad connection.There is also no guarantee that either one these methods would done correctly-I remember hearing that one of the problems with the crimp method was that some guys squeezed the c24 too hard and would almost cut the wires in half-this method of tying togther cccs is NOT friendly to the unfamiliar and neither is soldering.
Next comes the issue of insulating those joints: Most ropers today have come up during a time when applying tape insulation to a joint isn't as common as it once was and as a result don't know how to tape a crimp/solder joint correctly or apply heat shrink-this is a huge reason why a return to these methods would worry me. They do sell caps for the crimps, but invariably many ecs will embrace scotch 700 or less ($$$).
Imo, while these are both good sound methods and they are still listed, much like shallow sectional boxes and the bracebits used before routing k&t, they also have their place in their rearview mirror or a museum when it comes to new residential-Be thankful for modern products.
Wirenuts have been used regularly for over 4 decades and are cheap, idiot proof(most of the time), easy to inspect/remove, and reliable when installed correctly.