At one time, I was flying the Viscount as first officer and the Aztec as single pilot. There wasn't a problem.
I then went on to the TriStar. Far Canal! Vertical learning curve. Strange Lockheed switches and aerodynamic bits. Great flight deck though.
The B747 was a bit retro but a much easier conversion and the B744 sooo easy by comparison. It was more difficult going back to the B747 after being spoilt by the pink string, speed trend arrows and great ground effect wing.
Extra performance sometimes initially appears a handful and then you wonder how you ever did without it.