One other semi-random thought... the only time I've had serious microSD card corruption was when I was first playing with kernel-power and experimented with the "starving" settings.

They appeared to work fine for most normal phone use and I was on the verge of replacing my microSD when I thought to check "what have I done recently?". Returning to the "ideal" voltages solved the problem and I haven't had any problems since - so, if you're doing any major undervolting, try changing that before assuming your SD card or filesystem is shot.