So... I haven't DM'd in a lot of years, and in those days it was mostly a question of Basic or Advanced D&D rules until some 'other options' came along. You know, like Traveler, Car Wars, Twilight 2000, Battle Tech... Interesting to see your discussion as we use to try to modify the rules for better realism. We didn't have DF (or any other computer game for that matter) to base it on but rather tended to try to merge rules from different games to try to make something better.
In reading your post, what seems to be missing is hit location. DF seems to determine location of a strike prior to damage and damage is dependent on what is located there. There is a REALLY old RPG called "Fantasy Wargaming" that was never really quite finished but had a good partially complete rule book (with a similar magic system you describe). What was neat was a 'location' role on a percentile basis instead of a 'to hit' role on d20 basis. The higher you rolled, the better the location. You then had modifiers on experience (no levels in Fantasy Wargaming, like DF) so you could get in the above hundred area. Shields, dodging, parrying, etc. gave a negative to the role. We also played it with a cascade on 96 to 100 to add some randomness. Once location is determined, you could then determine what armor was covering that location and determine a modifier (sounds like DF...). At that point, I can't remember the original Fantasy Wargaming rules for damage (this was well over 20 years ago), but I think we did a dice role and added bonuses for the weapon and minuses for the armor. Positive difference meant wounds, lost HPs, etc., zero or negative nothing. Later we added in the Role Master critical charts for gore, but that was a good ten years later...
As stated earlier in a post, fun is the most important rule though. Not only for players but especially for DM's! What usually ended a good game in my days was the DM got sick of the players squabbling over gold pieces, the player who spent hours discussing if and how he can go about making bread or find a general store and talk pointlessly with the merchant while the other players wanted to kill monsters, and, of course, the power gamer. Ugh... cheating on dice roles for attributes? Why?
I found when I explained from the beginning that (1) don't get attached to your character because they are going to DIE, (2) no battle will take over 2 hours or your character will DIE, and (3) if one character is being annoying, he/she will DIE, it remedied most of the problems. I did have to make every character that was ever rolled up and ventured into the world a few examples though... That said, I eventually burned out on it from those exact problems and haven't played (or wanted to play) a RPG for a couple of decades. Lesson, important to have fun yourself as the DM. DM's put in the work (as you seem to have done), players just roll some dice and paint a miniature or two...