Also consider Aim +20 is 35 clock ticks, which gives it an attack speed of 100 / 35 = ~3. So you you would actualy have to use two+ of your characters turns to complete the attack.

If you have a speed of 9 you can use Aim+5 3 times in the time you could use Aim +20, which is far more damage for virtually any weapon setup except unarmed.