Love the write up, particularly this section about the RNG. Do you mind if I shamelessly steal borrow some sections of it for my own homebrew?
Steal away. A large part of the fixing the RNG was lifted straight from Legend (though some of the changes were my own. Keeping higher armor values and varied armor, while reducing base AC for example).

I do have one or two little issues that are still niggling at me though. The first is linking the scaling of AC to BAB. The medium BAB classes (rogues, monk, TWF rangers) are in melee combat nearly as much Warriors and Paladins, and there is no guarantee the demon you're fighting won't turn around and try to gib them, or that the horde of orcs will all line up and politely wait for a shot at your party's meatshield.
Rangers: Already have full BAB. Think you're confused here.

Rogues: Have dex as a primary stat, by high levels they could have a slight AC advantage there (especially if you use my armor system, where max dex costs half as much as a flat armor bonus).

Monks: Should have full BAB anyway. But besides that they have an untyped AC bonus, and wisdom as a bonus to AC. If anything I'd be worried about them having too high of an AC, not too low. A 20th level monk could end up with something like 5+15(BAB)+8(bracers of armor)+8(dex)+6(wis)+4(monk bonus)+2 (deflection) = 48, with relatively low attributes.

Basically Rogues seem like the most likely to suffer, but they're traditionally relatively easy to hit and squishy, so I'm not sure that's a bad thing. They won't be so squishy that they're unusable, they'll still dodge some attacks, they'll just get hit a bit more than the guy with a heavier combat focus... which is pretty much the intent.

The second thing is, since heavy armor is now definitely better than medium or light armor from a pure defensive point of view, can we either increase or remove the Max-Dex Bonus? At higher levels, it's restrictive enough that some Dexterity based builds forego armor entirely, and under your system that leaves them very (comparatively) squishy.
Or are you worried that higher Dex scores will combine with your improved AC to make some classes untouchable?
This is a reasonable request. But yes, I am worried about having armor bonus and unlimited dexterity. Having that situation makes it harder to control the RNG. I could see maybe some way of scaling max dex at higher levels (special materials giving a little more leeway, or adding enhancement bonus to max dex, so padded armor at level 20 would have like 13 max dex, which is enough for the majority of characters while still having 7 armor of its own).

Alternatively, using my equipment system (see the topic Weapons, Upgrades, and More) allows for higher max dex via masterwork upgrades, or crafting a weapon with a higher max dex from the start. You can increase max dex by 2 for the same cost as +1 armor, allowing for a bit better scaling for high dex characters. (the top end I believe would be a custom masterwork heavy armor with all slots going into max dex, giving you +2 armor and +20 max dex). [yes, it doesn't make a whole lot of sense that heavy armor has a potentially better max dex, but the idea both there and here is heavy armor is supposed to be a harder to get proficiency. Heavy Armor requires both light and medium proficiency. Because of this it should be strictly better, just not better enough that everyone without it is totally gimped)