Mirk,
I appreciate the insight. I don't claim to know everything and again don't have a lot of miles on my prototype yet. It is definitely something I will keep an eye on. If you don't mind me asking what exactly failed? Did the hub break? Did the freewheel mechanism fail?

From a business standpoint, I think that this decision should be up to the customer. Whether they use a standard derailleur, an internal or a NuVinci will be up to them. At least this gives them the option of both gears and type of rear hub they use.