I just stumbled across a weird build for a Sunder that is working really well!
HIL, Graviton, Ion Pulser, 3 vulcans, and sabots. ITU + 20 vents, 17 caps, with a reckless officer with energy weapon mastery (elited), gunnery implants, and target analysis. This build was a "whatever I have lying around" fit because I recovered a Sunder with only the -hull D mod from a fight and coincidentally got a 'promote from fleet' reckless officer with energy weapon mastery, so decided to give it a try.
I originally thought the Ion Pulser was going to be useless thanks to the range mismatch, but it is doing really good work! Most of the time it doesn't fire and the ship does the usual artillery sunder thing, minus a graviton. But thanks to the reckless officer it is much more willing to close in on enemies when it is winning the flux war and when it does the ion pulser is often enough to cripple the enemy ship. The same happens to enemy frigates that try to rush the sunder. The sabots on top give it some alpha strike anti-shield on top and whatever target it comes across first usually doesn't survive.
This ship is in a mid sized (~85 DP) early game destroyer/frigate fleet, and I am careful to make sure the Sunder isn't alone so it has another ship around to provide kinetic anti-shield support/flank coverage. It is MVP any time I'm dealing with capitals as the HIL armor cracking + ion crippling to keep my ships alive is just so clutch vs one big target. I should add that I'm flying a pretty standard Hammerhead (Arbalest + Heavy mortar + railgun + light assault gun, reapers, ITU, insulated engines, RFC) and will often fly near this sunder, both to protect it but also so that I can charge an enemy I want dead and flux out their shields for the sunder to do it's work.