I only had battery life problems with the Atom 1.0 although Oceanic has made it clear that the quality of some of the coin batteries on the market is below par and only high quality batteries should be used.
It was explained to me that the Atom 1.0 had a single processor that was shared to function as a PDC and watch. The Atom 2.0 has separate processors for PDC and watch function and uses significantly less power when notbeing used as a PDC.
I’ve used Varta, Duracell and Eveready batteries in my other computers and the battery life seems reasonable depending on the frequency of use.