Teaches me for assuming.... from the spec sheet:
8830: 900/1800 MHz GSM radios (Europe/Asia)
9630: 850/900/1800/1900 MHz GSM radios (NA/EU/Asia) and 2100 MHz UMTS/HSPA
So the real question here is what will happen if I go into an area with AT&T service but no VZW service... will I hop on the AT&T network?
However, I'm still assuming the Tour will never come to AT&T/TMobile - it would be useless to carry around that CDMA radio (instead of WiFi).