You also forgot that the iPod Touch has half the RAM (256MB) of the iPhone 4 (512MB)... I think. The game probably wouldn't run nearly the same.
I also forgot to mention how even if you play Citadel or on your iPhone and it ran at a perfectly smooth frame rate and it was the best looking game ever on a handheld, you would still only be able to do it for no more than 2-3 hours on a full charge, and this is on the device you carry around in your pocket to make and receive calls/messages all day when your not home to sit next to a charger.
comparing the 3DS to the iPhone is like comparing apples to genetically engineered super fruit.