Not sure about the whole not spinning at low rpm... somehow i find that highly doubtful.
N1 water pump goes 2 more fins for nine in total, where as the normal one has has 7. The n1 water pump i dont think it is that much more then the normal one... maybe 50 or 70 bucks only.
So, if i was you, i would just get the N1 pump as its only extra ~ 70 bucks. However saying that,,, the normal water pump well work perfectly fine for street.. and if want to keep that 70 bucks for a tank of fuel instead! Then theres is no problem in that either~!