The factory Nav provides so much information beyond mere gps that it's just an easy decision for me. It's virtually a vehicle control interface that I can't imagine riding without by now. Not to mention the control by the fly wheel. The powerful functionality more than justifies the price, in my view.

ETA: I don't think the price of the Nav is a small change. At 1/24 of the vehicle price it IS actually quite expensive, but so is the ESA, the LED headlight, the ASC, and all the other options that make our BMW motorcycle a perfect riding machine. I would say don't leave out this one piece that makes your bike perfect