… until developers begin targeting the A8X specifically …
That is kind of absurd. The difference between targeting the A7 over earlier CPUs is pretty big (64-bit instruction set) but for the lionshare of typical use apps, A7->A8(X) is pretty trivial. A few intense games or scientific apps may need to use the extra GPU heft, but even that is not all that likely; when viewed especially through the lens of mom&dad-lite use (per the OP), it probably will not matter. I would be more concerned about the 1 vs 2 Gb of RAM difference.