I would be very interested to hear from people that have installed the Ohmmu battery as I am thinking of getting one. I am particularly interested in anything known about the issue of charging below 0 °C. Does the unit have a heater in it or does it just disable charging when below 0? Also note that LiFePO4 chemistry is generally accepted as having a useful lifetime of > 5 years though these folks limit the warranty to 4 yrs. I don't think Ohmmu has been, in any of its incarnations, around for more than 4 years so I don't expect anyone will have any longevity data.