Thing is that the AK100 can go as high as 162GB of space while the X3 can only do 64gb max. And when SD cards higher than 64 come out it will do much more than that. Space is a feature that carries a premium.
Using a MicroSD to SD adapter I have a 128GB SD card on my X3. So yeah, it's not 162 but it is less than half the price.
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