rx7ttlm has some good points.
I'd also like to add that all of my main wins, and every position gained, have been because of the NT1's durability. Simply put, the competition had far more problems with popped belts, stripped gears and broken parts (after contacting a wall, disc or other car) than my XRAY.
Almost every time I had a bad main run, losing position(s), it was always caused by motor issues due to my lack of talent in that area.
With that in mind, I'm pretty sure that the reoccurring costs of racing and maintaining the NT1 are definitely on the low side of the manufacturing totem pole, regardless of the higher priced parts. The extra track time gained is also priceless.