I put in the first card indoors, before leaving for the expedition, and when I changed cards they had the same temp as the unit had so there should not have been any condensation phenomena. I scanned in the open. I know these issues appear also at -25 C, but the slow card performs well at -15 C ( 5 F) (The fast card causes data loss at all temps). These temps do not tempt for excursions or fishing trips, but I was curious to see where the limit is.
I think the overall low temp performance of the unit is quite impressive. The display doesn't freeze (as the external Garmin GPS disply does), the buttons feel like in warm weather and the unit seems to process all menu settings as usual. The transducer cable gets very stiff though.
Rickard