A Quick(ness) alternative to Armor (Class)

When I wrote 10 alternatives to Armor Class, I didn't think of this one. But now I've been writing about opposed rolls and this idea makes perfect sense. I'm sure some edition of D&D, or other game, must have done something similar, but I can't remember any examples.

If you do, please let me know in the comments!

Curiously enough, it is quite the opposite of of the WFB system described in the post that inspired me in the first place.

This example assumes Ascending AC (unarmored AC of 9, 10 or 12, doesn't really matter).

Here is the idea: if you get hit by an attack, you can roll a Reflex/Dexterity save to dodge the attack (probably no more than once per round; use a Reaction, etc.). The DC is equal to the attackers roll.

Pretty simple, right? But it is incredibly effective because:

- If your armor is good enough, dodging in often useless (the roll required is just too high).

- If your dodge improves as you level up, it can make up not only for armor, but also for magical armor bonuses (the numbers must be fine tuned, of course).

- Armor is useful when fighting multiple opponents, dodging is very useful against one single opponent.

- It is a very fun feature for a Thief to have, even if you don't allow it for everybody.

- It makes dodging feels riskier than wearing heavy armor.

- It does away with the need for limiting Dexterity bonus to armor; now they are separate things, and amor just makes dodging less useful.

- It makes one-on-one dueling a lot more interesting.

- It opens up new possibilities of using shields and parrying weapons.

There are some possible downsides to this. The first one is that it will be often frustrating to fail you dodges, but saving throws aren't required to be a sure thing anyway. It may also feel unnatural or intuitive: you see if the attacker beats your armor BEFORE you try to dodge.

And, of course, if you allow everyone to take this option every time they get attacked, combat will slow down significantly - which is why it is probably a bad idea to give this option indistinctly.

But, overall, I think it is a nice alternative to most solutions I've seem around.

It seems like something like this would work well with 5e and maybe even Pathfinder. It wouldn't be hard to use it with TSR-D&D as long as it uses Ascending AC, but even with Descending AC it might be possible to use a similar idea (since you just have to roll higher than your foe).

What do you think?