Would Ernst Röhm have been competent leading the Nazis if Adolf Hitler was either killed or never became a party member?

The SA were not the core of NSDAP, it was not a hierarchy with Ernst Röhm possessing power of life and death over those beneath him, rather the organization existed and grew in strength due to Hitler's showmanship, connections and ideology.

If Adolf Hitler was Taylor Swift, Ernst Röhm was a functionary, her sound technician. If Taylor Swift dies then her closest associates might make a tribute to her and make similar music, like the Foo Fighters continued on without Kurt Cobain.

>>17864962 (OP)
No. He thought Hitler's strategy of electoral paths to power were contemptible. He thought that just overthrowing the government was the best way forward, but that meant that the military would always be on the side of the government. He would have tried multiple putsches before being either killed or imprisoned for good in an centrist crackdown on far right and left extremists.