Accuracy Mechanic

So, 95% the way done with battle mechanics, I decided by system for accuracy needs a tweak. Here goes:

You roll a d20, 2/20 chance to miss, 4/20 to hit arm 4/20 to hit leg 6/20 to hit body 4/20 to hit head. Hit head is a critical, I like the statistics they are fairly balanced.
Then, you add Mods...
+1 Acc = -1 Miss, +1 Head.
+2 Acc= -2 Miss, +1 Head, +1 Body
+4Acc = -2 Miss, -2 Arm, +1 head, +1 body, +1 Leg, +1arm (For a net of -1 arm in the end).
ETC ETC.

+1 Head = -1 leg -> 2/20 Miss 4/20 arm 3/20 leg 6/20 Body 5/20 head
ETC ETC

Each part of the dice is assigned numbers after determining the statistic.
Confusing? I think so. Gets the desired effect? Yeah, pretty much.
There are a few other exceptions and rules that do things, but aren't in question here because they aren't changing.

So, instead I thought of
5 dice
2d4-2 = Miss (Subject to change)
1d6 = Arm
1d6 = Leg
1d8 = Body
1d4+1= Head

You roll, which ever gets the highest, you hit. Like, say you get an 8 to body on a standard roll, and other crap on the others, you're gonna hit body.
For Mods: Miss Chance Bonuses are added to the Miss roll,
To hit a specific part is added to that die.

Plus, I hate d20's, I like to use only d4's d6's d8's.

So, the questions are: Which is more simple to understand? Which will work faster? Which will allow for better variations? Which has reasonable fairness?
And, if the second system, what d4 d6 or d8 combination could I use that would make a miss chance roughly between 7% and 13% ? It's probably pretty close now, but yeah....