the Xbox One SOC has 32 MB eSRAM on die so bandwidth demands could be managed so as to no hurt performance. also Xbox One GPU's bandwidth demands are going to be lower. But there is no going around the fact that PS4 GPU is 50% faster wrt Xbox One. Thats definitely a huge gap. also the SOC die looks huge as its a 5 billion transistor die , out of which 1.6 billion is for the 32 MB eSRAM. In fact it looks like Sony PS4 SOC die will be smaller as it would not have this massive SRAM on die.
Microsoft looks to have a larger die and much lower GPU performance. But Xbox One will run cooler because of a much smaller GPU and DDR3 which draws lower power than GDDR5. I honestly feel the tradeoff Sony made is better. Even if multiplatform titles are developed with Xbox One as the base , developers can run features like 4x MSAA on Sony PS4. As for Sony exclusives they are going to kill the Xbox exclusives in graphical fidelity. Games like God Of War, Killzone, Gran turismo should be a treat to play on PS4.