I have an unlocked international-version Galaxy Nexus on the German T-Mobile network. It's only about a week old, but more than once in that time I've seen the signal drop completely out, and won't come back until I reboot -- and sometimes not even then. In the same location, my old AT&T Captivate (rooted, running a custom ICS ROM) gets 2-3 bars of signal, around -100dBm. I've read a lot of Verizon users complaining about the GN's radio, but I haven't heard of people having problems with the International version.
Is this fixable? Are there newer revisions of the phone where this issue is fixed? If not, does it vary between individual handsets? Would exchanging it for an "identical" handset stand a chance of getting better hardware?