I am starting to think this is some correlation between the radios the Nexus and s3 uses and verizons CDMA service. Not that I can prove it, however. I love my nexus, I really do, but the service, frankly, sucks. I am mostly on 3g anyway inside at work, but the speeds suck, most of the time hitting less the a meg! It has failed and stalled when I needed it most. Trying to get a radar image for the weather (I am a huge weather nut) and trying to tweet photos, often times the bar will be 3g with NO bars. Seems like the device cannot even hang onto a 3g signal at times.
Seems my moms note does a better job at work then my verizon nexus does.
Oh, there is no AT&T 4g here in Denver (yet) but the HSPA+ seems to have decent speed, got about 8 mbps at work. I think I would take a slightly slower connection that is pretty much constant and there, then an erratic signal.