If the Atom had provably more horsepower than the better ARM processors ... maybe. Assuming the battery life was still at least 6-8+ hours (reliably, under full work load ... and to compete with the iPad, you'll need AT LEAST 10 hours). But, in cases of comparable product, the ARM cpus seem both faster AND less power hungry than the Atoms... so the trade off is not "horsepower vs battery life". As far as I've seen, ARM wins for both.

Instead, the tradeoff seems, to me, to be "do we want general x86 compatibility" (even just within Linux). I don't care about that, so I don't find that to be an acceptable trade.

Though, if you're talking about non-Atom x86 CPU's... good luck getting 10+ hours of battery life in a tablet that's comparable to the iPad, using something that has better than Atom horsepower.