As you said, call quality is unknown, but I'll always give the edge to Moto on the odds.
If the GNex has bad call quality or non-functional GPS, or poor reception, its use to me as a phone is worthless. In that case, it would be a slam dunk, for the RAZR. An HD screen and faster GPU to show me that I dropped a call? No thanks.
I'm not trying to speculate, or start anything. I'm hoping the Gnex is all that it can be, and then some. If so, then it's a keeper. If not, then I'll move on. Simple.
I've had bad experiences with Samsung phones in the past. Most have been form over function. Pretty looking, but with some bad functionality (SGS GPS anyone?) coupled with horrendous software and support. Moto has always been function over form. Not the nicest looking phones, but solid performers. I've never once had an issue with the build quality or phone quality of Motorola. However, Samsung has shown some tremendous improvements in these areas. I'm willing to give them the benefit of the doubt, especially since they won't support it (comes direct from Google). If Samsung support was involved, that would be more of a deal breaker for me than pretty much anythng else.