I think this excerpt from Kelvin Zhang's (from GPD) interview is pretty interesting with regards to the microSD card sizes:
A320: The majority of Chinese manufacturers have described their devices as compatible with microSD cards "up to 32 GB". In fact, most of those devices can use a 64 GB microSDXC cards as well. Why "up to 32 GB" then? Also, is it possible to have two active microSD slots in one Android device or handheld device with reader of full-sized SD cards?
Kelvin Zhang: Maybe because it?s the maximum capacity of TF cards available on Chinese market, and that?s advertisement talk. Although, yes, our devices suppord cards up to 64 GB. Maybe we should change it to ?64 GB? to satisfy consumers, to let them feel ?more powerful?
. Two SD slots aren?t that necessary as we consider, and it?s also too difficult to be implemented. Full-sized SD slot? well, I think it will be difficult to put on the PCBA of a handheld device, but maybe we will use them in our TV-box.http://boards.dingoonity.org/gpd-devices/%28coming-this-week%29-interview-with-gpd/