I ordered a 64GB micro-SDXC card from amazon.co.uk a week ago for GBP45.39 (found on HotUkdeals). Arrived today (was listed as "usually despatched within 1 - 4 weeks"), h2testw confirms capacity, and works fine in my HD2 running WM6.5 (Energy ROM), which shows capacity as 60906MB.
I don't understand why so many jump in saying a 64gb card wouldn't work when they obviously haven't tried. i would assume that it work fine as long as its formatted fat32... Any android phone should accept 64gb cards as well. the only difference between sdhc & sdxc is the formatting Im pretty sure. sdxc is formatted exFat of something like that, but its easy enough to reformat anyway you'd like with a computer.
I have the Sandisk 64GB microSDXC Class 6 and it just works as a 32GB Samsung Class 10. The Sandisk is just a little bit slower in Benchmarks but in my phone I can't feel any difference; besides of the double of space. ;)
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