Since I started reading this thread, I had to try this myself. I have a Verizon Iphone4 and my nephew has a AT&T Iphone4. At the office we are at, there is a consumer grade Linksys router (don't know the exact model). We both connect with same amount of WiFi bars. Downloaded an app (40MB game) from "App Store", went to numerous websites and downloaded a data file (5MB) in email for testing. All test were basically equal. Websites were the same amount of time, data file in email were same. These tests never had more than 1-2 seconds different, with phones alternating who finished first. Only game file from "App Store" was slightly apart (about 10 seconds) with my Verizon Iphone finishing first. Those were my results for "layman" test.