Disruptors are a little weird. All the disruptors have the same damage, but the differences are in range.
I can't say what a disruptor is like in a starbase siege, due to lack of experience, BUT, in a Starship battle, I feel that disruptors have two points from which they can build an advantage on: Turn Rate and Wide Firing Arcs.
Turn rate lets you dip in at a steep angle and turn out quickly to back off, Wide arcs let you throw them at a steeper angle so that you have less to turn out.
BUT, both of these are only in an SFB context. Behaviour of the weapon is very dependent on what ship the weapon is mounted on (not in a technical manner, but rather how its used).
I would take a look at Corbomite's thread (somewhere) - it has all the weapon charts written out.