By the way... Jim, I wasn't knocking you with the BT post, I'd written that and then finished it during class but I couldn't post it until I got back into a Wireless area. =p Didn't see yours before I posted mine.
Continuing the saga of the 0 DPS, 1400 AP man with 30% crit and 14% hit, let's look at the offhand. For reference, this is the mainhand;
Parry: 100 x 0.00 x .0000 = 0.0000
Dodge: 100 x 0.00 x .0560 = 0.0000
Miss : 100 x 0.00 x .0136 = 0.0000
Glanc: 100 x 0.65 x .2500 = 16.2500
Crit : 100 x 2.00 x .3000 = 60.0000
Hit : 100 x 1.00 x .2580 = 25.8000
Total: = 102.0500
And this is the offhand.
Parry: 62.5 x 0.00 x .0000 = 0.0000
Dodge: 62.5 x 0.00 x .0560 = 0.0000
Miss : 62.5 x 0.00 x .0136 = 0.0000
Glanc: 62.5 x 0.65 x .2500 = 10.1562
Crit : 62.5 x 2.00 x .3000 = 37.5000
Hit : 62.5 x 1.00 x .2580 = 16.1250
Total: = 63.7812
Now, combined we get 165.8312 damage from our happy fellow here. This is also the % we multiply his tooltip damage to determine what his actual damage is (using this parameters), no matter what his AP works out to be. We can combine the two tables as follows, simply adding the mainhand and offhand in since their chance to perform each task are the same.
Parry: 162.5 x 0.00 x .0000 = 0.0000
Dodge: 162.5 x 0.00 x .0560 = 0.0000
Miss : 162.5 x 0.00 x .0136 = 0.0000
Glanc: 162.5 x 0.65 x .2500 = 26.4062
Crit : 162.5 x 2.00 x .3000 = 97.5000
Hit : 162.5 x 1.00 x .2580 = 41.9250
Total: = 165.8312
Adding in 8 Crit will increase his crit chance by .0035. Adding in 8 STR will increase his base damage by (8 / 7) * 1.1 ^ 3 * 1.625 = 2.4719. Running the numbers again, at our current parameters an 8 Crit gem will increase the damage multiplier by .0035 and 8 STR will increase the base by 2.4719. This means that you have to determine the point at which (again, using this table) increasing the multiplier by .0035 will cause a larger increase than a base increase of 2.4719.
With our hit/crit numbers, this works out to a combined base damage of 706.2571, or a combined weapon/AP total of 434.6306 on the mainhand, or 6084.8284 AP, or 4684.8284 AP with 100 DPS weapons.
So... in our very limited demonstration, AP causes a larger boost to autoattack than Crit does using fairly common numbers. It's worth noting that there would be absolutely zero effect on the final number based upon your current crit%, but modifying the hit% would have a significant impact.