Get what you need now - don't worry as much about resale, unless you're planning on selling it in the next 6 months.
If you need 512gb, pay for the upgrade. If you can live with 256gb, personally I think it's probably the better option because you have to assume that SSD costs will continue to fall.
Another thing that I think will happen in the coming months/years is that you'll start to see SSD external storage replace HDD. And with that, if Apple and Intel's bet is correct, they will be connected via TB, making them almost indistinguishable from an internal drive (as far as speed goes).
But I'll go back to my original comment - get what you need today. WIth any Apple product, it will maintain at least a good resale value and if it satisfies your needs now who really cares what you may or may not get for it when (and if) you want to sell it.
If you need 512gb, pay for the upgrade. If you can live with 256gb, personally I think it's probably the better option because you have to assume that SSD costs will continue to fall.
Another thing that I think will happen in the coming months/years is that you'll start to see SSD external storage replace HDD. And with that, if Apple and Intel's bet is correct, they will be connected via TB, making them almost indistinguishable from an internal drive (as far as speed goes).
But I'll go back to my original comment - get what you need today. WIth any Apple product, it will maintain at least a good resale value and if it satisfies your needs now who really cares what you may or may not get for it when (and if) you want to sell it.