Sorry, but no. Once TSFS introduced the NX for experimental starships, that's the way I roll. But I do think that NX is a temporary registry for a brand-new design ship that is converted to NCC once it goes into mass production (I personally think that was the case with the Excelsior in TUC).
ENT did something a bit different with NX registries, but that was in the pre-Federation era, and the NX-class was the end result of the initial NX Program, anyway, IMO...
It gets confusing when Star Trek mixes both naval ship and aerospace nomenclatures and concepts. It's sometimes difficult to reconcile the two.
The United States Navy does not give an experimental designation to the first ship of a class, even if the ship is undergoing sea trials and has not been comissioned. It reserves the designation strictly for ships testing new technologies, such as the IX-529 Sea Shadow.
That was just nonsense on the part of Star Trek: Enterprise. If a ship has an NX designation it should be experimental and be testing the new technologies. It shouldn't be in service performing missions. Where were the yard engineers on the NX-01? Where were the flight recorders sending telemerty to the yard?