Parrying on MOG

In my MOG campaign we use a parrying rule as opposed to a fixed AC bonus.
-----------------------------------
Parrying
High DEX does not constantly improve AC, a combatant may choose to parry/dodge to gain a benefit of high dexterity but in doing so they loose access to their normal attacks in a round.
Missile weapons may be parried at any range if bearing a shield.
You may only dodge range attacks made from long range or dodge any attack if you have partial cover.
DEX
3...... parry +1 to AC
4-6.... parry +2 to AC
7-14...parry +3 to AC
15-17...parry +4 to AC
18-20...parry +5 to AC
21+.... parry +6 to AC
-----------------------------------

I opted against including a modifier to parrying based on initiative or weapon speed factors in interest of simplicity. I'm providing an advantage based on player tactics not a one time lucky roll of the dice alone. Each round a player must wonder... is it worth parrying now and losing my next set of normal attacks?

Not a brand new rule, it has it's roots in the first RPG I ever owned, it just needed a little tweaking.