The shaft of enlightenment wasn't enabled by an overflow of bits and memory space. To abbreviate a very long explanation that sounded more like rambling... the ground is used to attack your dwarf, an upright spear is used instead of the floor but being a weapon requires skill use, skill is based on swing speed because inanimate objects don't have skills, the ground "swings" faster than any creature ever could, your experience is based on the "skill" of the opponent but in the case of upright spears is the speed of being "swung". Final result is an attack from a Godlike opponent that trains you irrationally well.
Why it never worked for falling 4, 6, 7 and 9+ z-levels was never fully understood and might have legitimately been an overflow. (Which means 8 must have overflowed within an acceptable range.) I've never seen Toady address the phenomenon specifically, so
No, what really kills the shaft of enlightenment is the line right above OP's example:
- Capped various combat skill gains per action (Urist Da Vinci)
- Stopped "fighting" skill from increasing from trap/projectile attacks
My theory is that it still makes sense to train armor user, dodge and shield user from traps, but since you're not gauging an opponent when you're dodging projectiles and traps, then improving "fighting" skill is inappropriate. On topic, being able to train Godlike levels of skill from falling once on a willow spear isn't appropriate either.
Danger rooms and the shaft are still in, you just have to settle for training Fighter the normal way and marching your dwarfs off a cliff more than once.