Hardware Question About Purchasing MicroSD card for NEW 3DS XL

[Lakerfanalways]

I will be purchasing the NEW 3DS XL when it comes out on Feb 13th(Im going to the store to pre order the red one on Friday) I already have a 3DS XL that has the 4GB card and I have 26,000 blocks free on it. The new 3DS XL comes with the same amount of space so at first I was not considering buying a microsd card for the new 3ds xl..then I saw today's Nintendo club rewards and I saw Kid Icarus and Donkey Kong Country 3DS both of which I can get..I already own those two games but was thinking, mind as well trade in those two games at gamestop and get them digitally for free from Club Nintendo, but I would need to upgrade the memory card and Im not sure which one I should buy or what is recommended..Im thinking maybe an 8gb or 16gb is plenty for me since I don't plan on buying anything else. I am going to do the system transfer in store of the eshop games I already have on my 3DS XL so not sure how I would go about doing this