I've carried and used my reader in -15C or thereabouts, also left it in the car at -20C for hours. Page turning was slower, and I made sure I put it in a bag before going indoors (to avoid condensation, letting it warm up bagged out in the cold) . And I guess battery was drained more quickly. But my 505 is still alive
Also my gps lives in the car (coldest so far this winter has been around -25C) and it is fine.