The S4 snapdragon has a integrated world multimode, programmable architecture modem. It supports everything!!!
The One S/XL should support all future 4G networks in the UK (Not sure about aerial compatibility)
So, what happens when nVidia start marketing their 28nm integrated modem SoC in 2013? They'll say it's worse than Tegra 3?
Tegra 3 will consume 5-6W at max load. On average the 4.7" screen uses 1W and don't forget stuff like connectivity overheads. How big is the One X battery? 6.6Whr?
A good investment if you don't mind sub 60 minutes run time then