When I lived in Tennessee 10 years was not un heard of and the record I personaly saw was 17 years (factory GM), the factory GM batteries seemed to last the longest and the factory mopar ones were terrible, I worked at the dodge dealer and it was very common to replace 2 year old batteries.

Now in montana where it gets a lot colder none of them seem to last very long, oddly enough the factory mopar ones seem to be ok for a few years. If we get a car in now with a 4-5 year old battery it is often suspect in hard start conditions like -20* weather.

I think the battery life would probably be the same butt it takes a lot more to start a very cold -20* engine than a 40* engine so even though the battery might not actually be any worse it just seems worse because your car won't start.