Idling, sure. So far, every time, there's been a comparison at the same Wh, but the resulting devices never get the same Wh batteries. So it ends up being 2 hours to 10 hours, but by the time you get the smaller device with 10 hours, the more powerful device gets 4 hours--you can usually get a bigger battery for it, too, which you typically can't for the smaller device. For the monumental performance difference, you'll need something else to make that 10 hours worth it. There's a middle ground there, somewhere, but at ARM's current progress, and assuming they either (a) integrate big.LITTLE fully into their designs (so it's no worse on the integrator than than a single soft core), or (b) start racing to idle like Intel, we're a good 3-5 years out, right now, in the best case, IMO.