Ive carried the same guns (usually a full size with a reload, and a smaller back up), all year round, my whole life, and really havent found it to be much of a chore. Summers here are often in the upper 90's with high humidity, winters can be in the teens and 20's.
I think a lot of the "swapping" these days, is due to the availability of all sorts of "little" guns, and people not willing to, or thinking they "cant", dress around the larger ones. Its not a big deal really, you just have to "want" to do it.
“The enemy is anybody who's going to get you killed, no matter which side he is on.”
― Joseph Heller, Catch-22
Zeitgeist - The Movie