One big difference between the PC and PS1 version is that they replaced the knights on the last level with "Hell Horror" skeletons, everyone seems to miss this some how :D

That feels like just an emotional categorization. Low HP + mana exploits a glitch where the game thinks you are dead for less then a frame and there for does not apply stun to you, then the mana shield refunds you the HP and revives you before the frame ends.

Duping exploits a glitch where the game uses the same buffer for memorizing items being transferred from one location to the next and there are two items being transferred during the same frame, resulting in one item overwriting the other one.

From a technical perspective it's hard to see how there is any meaning full difference between the two. Both involve multiple things happening during a single frame then the developers had originally considered.

If they have to be categorized it's probably better to do so in terms of how much they spoil the fun of watching the run, or maybe how much it spoils the fun of competing.

"the DevX devx at some point clearly said they won't change it" This is the first I hear of that :D

4-tile was caused by monsters using a ray cast from you to them to see if they could hit but alignment when shooting in the other direction wasn't symmetrical. That has been fixed.

We have at least a couple of DevilutionX runners. How many should there be before it gets moved?