I'm sure there are some optimizations that can be done on the process but yeah, it isn't new. I don't think the NOx issue is significant because you can sequester them, but it does add to the expense and lower the efficiency(unless you have a source of animal urine and can use the urea maybe?).

Is the efficiency difference between it and the Haber-Bosch process small enough to be made up by the lack of transportation?

I wonder if the nitric acid is a benefit in places with alkaline soil and water chemistries?