Todd -
I've used both ACR and NC for RAW manipulation, and I believe that both can be used effectively as a first step in NEF processing. From personal experience, I have chosen to use NC for initial NEF processing for the following reasons:
1) The operating model is completely different for these two programs.
- PSCS takes a NEF as a series of components, then asks you for the recipe for how to put them all together and converts this into an image based on those initial parameters you supplied. Once the file is opened past the initial dialog, there's no going back and making adjustments to any of those parameters without starting from scratch.
- NC treats a NEF as modular, and maintains the components as separate entities: WB/EV/Curves/etc. are all independent and can be adjusted and readjusted as needed without changing the underlying sensor data. These adjustments can be saved as a unique set, which for me is a great thing as I learn new tricks and want to adjust things after the fact.
2) I love the color histogram that ACR uses when opening a NEF file, and I believe it is one of the main reasons that Chris101 is able to achieve good WB in his photos. Having said that, though, what I don't like is that you can't get back to it after opening the file (somebody show me how to do that if I'm wrong -- wouldn't be the first time

). Sometimes when you make other adjustments, it would be good to be able to go back and see the effect it had on the combined curves. Since NC treats all these as separate entities, it's easier to deal with in that respect. But I do prefer the user interface that ACR provides (when it's available) over NC's presentation.
3) For reasons that I've never quite understood,
for me it takes more work to get sharpness and good colors with ACR. Could just be that my initial attempts were frustrating with ACR, and my initial attempts with NC were much easier, thus I gravitated in that direction out of laziness.
The above all apply to my experience prior to attending Ron Reznick's session in Florida. Since attending that session, I have used his prescribed techniques for initial processing with NC, which are a great foundation for an effective and easily-repeatable experience in initial processing. I'm certainly open to other options (I love to learn new things!), but to date I haven't found a better way to process. Until I learn a better way, I'm sticking with that process.
I hope this is along the lines of what you're looking for. As always, YMMV (Your Mileage May Vary).