I too owned a 2000 Miata 5-speed. In the 6 years that we owned it (bought it with 30K miles) I daily drove it for 55,000 miles and towed it over 35,000 miles.
I then got the opportunity to trade it in on a FULLY LOADED 2010 6-speed Power Retractable Hard Top at the end of the model year.
I can tell you, there is almost NO comparison between your 2000 NB and a late model NC. While the layout is familiar, it does not seem that they are both made by the same manufacturer.
The 167 HP 2.0 liter pushes the NC much more than the 140 HP 1.8 liter did the NB and the suspension has been vastly upgraded to handle the increased power.
The steering wheel is vertically adjustable as is the drivers seat.
No matter how you drive (and I drive rather spiritedly), you will enjoy the 10-12 year improvement in the power, the handling, and the "feel" of a new Miata.
Please take my advice and go drive a couple of them. I think that you will be impressed and pleased with the upgrade, but remember that the automatic is still untowable.
If you drive one, please let me know what you think.