Jesse, I don't know about the comparative nature of conductivity between the PL259 and the N Type connectors, but I believe the big difference is the physical size differences these two connectors present to the characteristics of the coax. If the connector changes the dimensional relationship of any coax component then you will likely get an impedance bump.
If you compare the end views of these two connectors you will see that the N Type is much closer in the cross sectional dimensions of typical 1/4" coax---relative to the shield, insulator, and center conductor. In this manner impedance bumps (losses), most noted when using the PL 259 connector, are greatly eliminated when using a correctly installed N Type connector.
This issue is about the symmetry of all elements making up the coax, and the connector design and installation keeping the terminations of the shield and center conductor as close together as possible---in order to reduce radiation as much as possible at the coax connection.
Also look at the end views of some cheap coax compared to some quality coax you may have laying around. You may find it not uncommon to see the center conductor of the cheap stuff positioned off center in the insulation and it varies along the run. This variation in construction can also cause bumps and other variations in the impedance and velocity factor.
Conclusion: if we have to make a coax connection, we want the components of that connection to be as physically similar to the dimensions of the coax as possible, and in all respects---so the connection point appears as transparent as possible to RF.
If each connector is done correctly, does this make a noticeable difference in the CB area, probably not enough to really tell---except when using high wattage transmissions or operating higher in frequency.