I understand it, the reason Rapid Demise was so maligned was the association with shitty plastic Rapid Rise rear mechs. They often came on BSO’s and thus were badly adjusted, fettled or even on the end of a wonky hanger. And with limit screws hitting plastic protrusions, it’s not long before it’s in your spokes too.
Technically, it’s a better system- you have a spring moving the mech towards the larger sprocket, so the pressure of the chain against the side/teeth/ramp can be exactly “correct” thus you are able to get the best shift possible. Additionally, the spring force is constant.
Whereas IRL, with conventional shift the user is likely to exert the wrong pressure and vary it over time. They may not, for example, be exerting the shift force at the right time to align with a ramp.
Dual control I know nowt about.
