To be fair anything smaller then a cruiser I fit with Reinforced Bulkheads on the premise that it's probably going to die, but that's ok. Late capital ship fights have anything lesser acting as support, which the sunder does very well in my opinion.
In fact they pair very well with big ballistic spewing ships like, say.... the CONQUEST! (back on topic bby!)
Sunders get easily shredded by fighters, which is why I used to not like them, but these days I'm in a sunder craze with task groups of 8 of them escorting my late game capital fleets as they can easily catch and kill anything smaller then a capital ships notice.
They die pretty quick when shot, but what destroyer doesn't? The key is not to let them get shot by ships they aren't supposed to be fighting anyway.
And SO Sunders are the things of NIGHTMARES. If you thought SO hammerheads with chainguns were good at killing lowly armoured and defended targets, you ain't seen nothing yet!