I'd honestly be happy with a well geared/skilled bard. The reason I ask for a Cor is that wildfire rips through the puddings. It's not a deal breaker though.
Or a Good cor using Fire shot for 4k+ with the high damage guns and using Last stand for 6k+ ( a COR before Adoulin was consistently hitting 6k Last stand in there, not seen with new gun )
However, the biggest issue in NNI is movement speed, and I find Mazurka > Bolters roll due to the recast timer on Rolls. A COR can replace a DD however while maintaining a balanced party.