CliveL;
Re, "I suspect the zero bypass Ol 593 would take less time to spool up than todays high bypass engines. "
Yes, I think so. The A333 (RB211s) had a specific technique at high-altitude airports to ensure the engines were stabilized at about 1.1EPR before taking the thrust levers into the FLEX/MCT or TOGA detent. The thrust levers were taken to their detents 'gently', even as FADEC did control the acceleration. Even then, some surging was experienced, again at high-altitude airports, (CYYC for example).