There was a story a while back about an F-15E pilot ejecting at or just above the sound barrier when his plane lost instruments and went out of control during a night-flying exercise. The laundry list of injuries he suffered makes it HIGHLY unlikely that a pilot would ever intentionally attempt it except to save their own lives. Broken bones, ruptured blood vessels, ligament damage...the best ejection seat in the world will get you out of the airplane, but it doesn’t help against hitting a 700+ mph slipstream. About 10 years ago one of our F-15C Pilot Training students blacked out from Gs and woke up in a nose-down attitude going close to Mach 1. He punched out and survived. He was in the hospital for about a year recovering from "flail injuries" that are a result of the limbs flailing around in a high speed bailout. I was told that the student held the record for surviving the highest speed bailout.