The replace_armor option is really cool, but it makes Armor Toughness completely useless.
Perhaps add a config option to make Armor Toughness increase the rate at which absorption recovers?

Armor Toughness could affect "recover_delay". By default it's set at 160.

Say Armor Toughness reduces the time for the recover_delay by 4 per 1 Armor Toughness point. You would have to wait less in order for your shields to recover if you avoid damage.

A set of Vanilla Diamond Armor has 8 Toughness so that will take 32 away from the recover_delay, making it 128. If you have 20 Toughness that's 80 to take away from the recover_delay, making it 80 which is half the time it takes for your shields to recover.

There could also be a config option to change the value if one wishes to do so, such as making it be 5 per 2 Toughness, 1 per 20 Toughness... if you really wanted. A config to set a cap where recover-delay will not drop below this value if you have a lot of Armor Toughness.

Example: Minimal recover_delay 100, having 20 Armor Toughness with it being 4 per 1 will take away 80 from the recover_delay... but... because the Minimal Value is 100... only 60 is taken away.

Yeah, something like that would be cool.

I do agree that toughness is an important balancing point of armor, so it having some equivalent would make sense. Personally though, the main reason I ported this mod was for the normal behavior rather than the replace armor features, so I did not put too much thought into improving it.

I honestly don't plan to put too much work into this mod beyond what I have done already, but if I find inspiration some time I will look into it. I would also be open to a pull request if someone else wanted to code up the feature.

I wouldn't mind attempting this. Haven't done anything with forge before but how hard can it be.

I can't seem to push a new branch, is that possible or am I already doing everything wrong?

You will have to fork into your own repo it as you don't have permissions to push a new branch on my repository.