No need for NIK as I use Pixel Genius' Photokit Sharpener.
NIK would be of no help since instead of having an action invoking PKS, I'd have one invoking NIK. I'm trying to get away from the Bridge/Image-Processor/PS-Action process and leverage Adobe's native support for PKS.
I'm not sure if it's a question of licensing (maybe that's what Jeff alluded to in his reply) and that only ACR and Lightroom are licensed to use PKS, but if so, it'd be nice to have these rights extended to Bridge/Export as well. It makes sense to me.
I'm not sure that having PKS Output Sharpening built-into ACR workflow options to be particularly helpful given I don't have full control of my final output resolution.
Maybe it's just me...