I'd bet that the battery in the transmitter just isn't happy about the cold. The receiver shouldn't be drawing much power anyway, so the transmitter would probably be the first suspect. Seems awfully sensitive though, 55 degrees is far too warm to start getting temperature related issues.

I use a Planet Bike Protege 9.0, and I haven't had it not read properly yet. Last week I was riding at below -20*F (the onboard thermometer just read "--") and the display was barely readable even in bright light, but it was working and registered the same distance for my commute that it always does.

Personally I would never use a wireless, but I guess that's personal choice. I don't trust wireless all that much, plus they go through batteries at much more than twice the rate that a non-wireless does (mine uses a single CR3250, and I only have to replace it about every 18 to 24 months).

I don't even run wireless for my home network, except for one laptop which actually rarely gets used at home. I pull wires through the walls anywhere that a computer will be installed. My motto is, wireless might be nice, but wires "Just Work."