From what I've done so far, most of the images available to load on to microSD are made for 2, 4, 8 gb cards. I haven't seen much images available for higher unless you compile it yourself.
Most rom guides also suggest class 6 or 10 if you want to run the image off of the micro SD but to load it onto the internal memory, 2 and 4 will do just fine.
the image may be smaller but you can repartition your SD card to accomodate it
if you're using windows, the win32diskimager program that you do to write the image will do that automatically (though you do lose the rest of the volume you're not using)
Last edited by dlinfiniti; 03-18-2011 at 08:33 AM..