The problem I see is that the number of times I've run out of power in the tablets is 0, which is what I'd expect considering they have their own UPSs (the batteries) after all. Metadata only journaling is nearly imperceptible in terms of flash durability, but it creates an additional performance hit. Crashes are another story, and if we're to expect the kernel crashing a lot ext3 is the logical choice (or not , if some horror stories are to be believed...).