[criddell]

Is Linux the right choice? It feels so heavy.

Could you make a Linux handheld that can run for 30 days on two AA batteries? Considering Psion made theirs 27 years ago, it seems like today we should be able to get a year or more out of two AA batteries.

[dTal]

A Kindle 4 runs Linux and has a 750mAh battery, which when multiplied by 3.7V gives 2.8 Wh.A single AA battery has nearly 4Wh, so two of them give nearly triple the capacity of a Kindle 4. A Kindle 4 lasts for a good month under light use, by suspending the CPU whenever the user isn't actively interacting with the UI. You could certainly make a productive Linux-based PDA that ran for a long time on AAs, provided you wrote custom software.