I've been following this thread with interest (and on other forums out there) and still looking for more than anecdotal evidence about the slow down / reduced power with 1.6. I'm running 1.5 in cold weather without issue, but I do warm my batteries to at least 25ºC prior to heading out, and keep them warm in an insulated bag with a microwave "cozy" warmer. My last battery may have cooled to about 18ºC before it's used, but still plenty warm. I'm flying in conditions varying from -1ºC to around +5 or 6ºC. I have insulator pads on my TB47 but not on my TB48s. Even flying in sub zero temperatures the TB48s are always warm on landing, and I'm always cautious with power and never punch her out in cold conditions.
From my understanding, by using warm batteries and flying as above I should not notice any reduced power with the I1 on firmware 1.6 as it will not detect a cold battery and it seems the temperature is measured from the battery sensor and not the aircraft. Does this sound right? If so, I see no reason not to update to 1.6, and it may help out if for some reason the battery does cool down during flight, say when doing static multi shot panos.
Cheers,
Rory