So how is work progressing on this?
Slowly and ploddingly... I *am* working. A lot. But I'm also getting very little done.
I finally figured out everything about gun sway. One problem was that by crouching AND aiming, assuming no crippled arms or other penalty-inducers, the whole formula would zero-out, since there would be a "zero" in the penalty multiplier, and there's no "base" (so a * b * c * 0 * d = 0). So I implemented a base, which was tricky and tedious. But then when I got in the game, I realized that NPCs simply couldn't deal with the wobble. It worked great for ME, forcing me to really time and aim my shots carefully at low skill levels (I increased the penalties but proportionately increased the mitigation to those penalties provided by skill)... but NPCs were shooting wild, making me virtually invincible. I think the game approaches it as though the NPCs are always in VATS. After "fixing" the accuracy, I had to implement a totally new VATS scale, since everything came out to 0% with skills under 80. Well, that 0% transferred to those poor NPCs. Of course, skill-100 NPCs could hit me in the pupil from a mile away, equally unbalanced.
I had done all of it this way so that the skill=acc would equally affect NPCs. I put in a fix for NPCs, but then I realized how much EASIER it would be to simply proportionately increase out-of-VATS gun wobble via a hidden perk, and leave NPCs alone (mostly). Two days of work mostly wasted.
Then I spent two days trying to figure out how to force melee damage to scale or cut out with arm condition damage/crippling. The problem is that, in vanilla, arm condition does mitigate up to 10% of melee damage: that which is added to melee damage by melee skill. But in skill=acc, that is gone. There is, to my frustration, no way to make arm condition affect melee damage (from NPCs) in a non-skill-based damage scenario. Not without adding a script to every NPC and creature, many of which have a script already on them. It's frustrating that melee damage doesn't scale with skill in skill=acc, but I can change that for the player pretty easily, and NPCs don't need it scaled by their skill, honestly. Since their skill is directly applied to their to-hit chance (which we humans can mitigate with a mouse and timing/etc), that's enough. I can do something similar for arm-condition, but since I can't affect NPCs that way, it ruins my "tactical combat" intentions, at least for melee opponents.
So I'm actually spending day after day working on XFO... often all day. But often with nothing to show for that work.
If I can get people to stick around long enough, this time won't be wasted since I learn more and get craftier.

I'll put out an as-is release before Christmas hits... I do have some stuff done