I have motors with just about all of the choices out there . Qjets, Holleys AND dual Edelbrock clones on my 470' 409. Can't say to Cliff's long term issues but 25 dyno pulls tweaking rods/jets as well as lash and timing I think they did OK
they were not OK out of the box. float levels not even to Edelbrocks specs. A step leaner jets also.