Another thing to consider here:

To get the +10% Accuracy from an ACC mod requires 4-5 in Targeting...a T3 skill.

To get the +2% Critical Hit from a CrtH mod requires 9 in a weapon specialization (separate for energy and projectile)...a T5 skill.

The 9 specialization though, will also give you +25% CrtD which is better than the +20% from a CrtD mod. But it's a T5 skill...costly.

With nothing else (no traits, other gear, etc, etc, etc)...

5 in Targeting (10k SP) with CrtH/CrtD mods on a weapon will give you: +11.2% Acc, +2% CrtH, & +20% CrtD.

9 in Energy Weapon Specialization (27k SP) with ACCx2 on a weapon gives you: +20% Acc, +2% CrtH, & +25% CrtD. Course, that's only with your energy weapons - not your torps or mines. That will cost you another 27k SP.

What's the difference in that to-hit against a target moving at 24 impulse (no other traits, skills, gear, etc, etc, etc)...?

+11.2% = 75%
+20% = 80%

Against a target sitting still (no bonuses, etc, so it's at -15%), what kind of numbers are we looking at?

+11.2% = >100% with +4.65% CrtH & +30.6% CrtD
+20% = >100% with +5.2% CrtH & +37.96% CrtD

So...10k SP with CrtH/CrtD weapons or 54k SP with ACCx2 weapons to get:

Moving Target
+5% To-Hit
+5% CrtD

Pinned Target
+0.55% CrtH
+7.36% CrtD

Yes, those are rough numbers - there are all sorts of things that could be involved - gear, traits, actual movement speed, etc, etc, etc... so keep that in mind.

But still - look at the cost in skill points...then look at the cost of the weapons on the Exchange.

I wish more of my guys were built around saying, "Sit!" at the target or that I ran with groups that said it for me...lol. As is, I tend to run the ACCx2 or ACCx2/CrtH weapons. On the gal I'm leveling now, though - I'm planning on going that ACC/CrtHx2 route cause she's got some "Sit!" in her.

edit: Thanks to pokersmith1 for pointing out where I was carrying a 1 in rushing that I should have - so I've adjusted the math.