Nuvinci internal gear hub

Has anyone seen/ used this hub in action? I'm in the midst of building my next bike (mostly for commuting and light credit-card/ supported touring).

DH suggested that I look into Nuvinci and set it up with maybe a dual chainring in front for extra speed. I'm really new to "internal gear hub", never rode one before. From this PDF, it looks really good. And DH says maintenance is a lot less then derailleur systems.

The cost seems pretty reasonable too ($450 U.S) since if I were to get good Shimano components, they would be up there as well. But would setting the bike up with dual chainrings increase its price?

Any PROS and CONS you can think of?

I do realise that it weighs more (4.2kg). And DH say I could look into Rohloff if that's an issue. Any thoughts?

Thanks!