Well, I have used only Phillips bulbs. So cannot commend on NB/NB+. Xtreme vision is a newer version after Xtreme Power. Though I cannot say it gives x% plus light, I can surely say that to a layman's eyes, the beam is much brighter.
I got a quote of 1200/- (philips XV's) for a pair at a nearby accessory shop.I think Philips authorised dealer will give a better quote as well as assurity of genuine product.