The A7 vs. A6 may not matter much now, but it will with iOS7and iOS8, the 64 bit architecture will be important for future upgrades.
If it A7 vs. A6 doesn't matter now, it might not matter later. How will it be important? Why do you want or need "future upgrades"? Why do you want or need iOS8? What is so horrible with what you have now? That's my point. If you are doing just fine with what you have, don't "upgrade" for the sake of it. Do it if there is something in the upgrade that you want or need. I know that Apple depends on people that just want to upgrade or buy a new phone only because everyone else is doing it but maybe it would be "different" and "innovative" if you upgraded phone or OS because you actually needed to do it or were not happy with what you currently have.