[Suicide Junkie]

The to-hit chance really does not matter...
You will do more damage per kt per turn with a larger mount regardless of accuracy.

Hitting more often with smaller shots is not an advantage unless the enemy has fewer hitpoints than the shot damage... and that dosen't happen in Stock SE4.
Any sort of regeneration / crystalline / emissive effect hurts the smaller hits far more as well.

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That said, there are mods out there in which smaller weapons are useful.
In such mods, the large mounts do not provide such huge power increases, and will have downsides such as accuracy penalties.