Upgraded to GN from a DX on Saturday at a Verizon store. Noticed a few signal drops while playing around with it, but assumed it was just because I was setting up to connect to WiFi. Upon researching the issue, this seems to be a fairly common problem. I've read about upwards of 7 factory replacements to get a functional device.
Updated the radio, but to no avail. Turning off 4G has solved my issue for now, but I don't really see that as a solution. I hate how much I love this phone otherwise; I was really excited to have a nexus device.