I believe that those early 727 accidents came from mistakes made by pilots transitioning from props to jets. The engines took a while to spool up from idle, and the landing flaps added a tremendous amount of drag. If you didn't anticipate the spool up time the airplane could get slow in short order. Also, I don't think the stabilized approach concept was universally accepted then.
After the UAL SLC crash (a merged Capitol Airlines pilot) Flaps 40 for landing was made optional, with Flaps 30 preferred.
My company (TWA) blocked out Flaps 40.
The 727 was quite stable on approach provided you knew how to fly a jet.
