If that "well-engineered carrier network" is using a 3G radio as part of the backhaul, it'll always be better to use the 3G connection reserved exclusively for your use than it is to try and share one with dozens of other people."A carrier Wi-Fi network should always be better than using a cellular Mi-Fi or air card," he said. "But I can't speak for every situation. Perhaps there are bottlenecks. But a well-engineered carrier network should deliver better performance. Air cards and Mi-Fi's are better used in places where Wi-Fi isn't available at all."