Probably the best write-up on all of this, is on the Magnecor website.
Aside from the massive amounts of EMI emitted from the Nology wires, which will screw up almost all of your electronic sensor readings on the car, there's no real disadvantage to running them.

OEM wires are relatively good, especially compared with the average aftermarket wire.
But, I'll leave it to any interested party to go hunt down and read the article!