I came here to spew a bunch of numbers but it looks like the janitor beat me to the punch. There may
be a case for leaving them as-is, as the raw numbers suggest that in the right setting, they do massive overall fleet damage. They never end up killing anything, and you don't really see any damage happen, so it doesn't make them an exciting unit, but that doesn't necessarily mean they're broken. However, it could be that with the way targeting and individual shotpower and all works out, their spread-out damage doesn't actually have a significant effect on the outcome of an ensuing fleet battle. Or it could be that it does.
Okay, here's the part that's actually off topic:
The above suggests that testing an identical fleet battle both ways (with softening up by attritioners and without) would be a Good Thing To Do, but of course with the PRNG, any two battles from a given save point are going to be so wildly different that the effect of the attritioners, if any, will be lost to noise short of a sadistic amount of retesting.
So, simple question: why not include a debug toggle that allows you to suppress re-seeding of the PRNG on reload (and anywhere else it might be triggered)? This would make it pretty straightforward to see if they actually "do anything" other than aggro, not to mention allowing for a whole bunch of other find-the-optimum-strat tests.
...unless, of course, that's what you're trying to discourage... on second thought, maybe keeping fuzzy mysteries is a good thing, prevents grind in the long run. Still, it'd be useful for this.
I don't have much of an opinion about this, but I have been meaning for a while to suggest a unit/turret be made which acts as a legit gravity well, complete with increased acceleration as a ship is drawn in. Hell, you could even use them offenso-tactically (http://wiki.uqm.stack.nl/Leyland_Gravity_Whip
). Dunno whether that would jive with existing motion code, of course.