I think it's less obvious. I have two coolers and 4 all-weather plastic bins with seals, and the plastic bins keep the humidity in / out better. Not huge amounts better, but I've also put gasket tape in the coolers to help them seal better. If you go with coolers, either get some with seals or inspect them to see if you can put gasket/weather tape in them. It was easy in one of my, perfect groove to use, and kinda a pain in the other.
The coolers do help buffer temperate changes short term, but over the course of a week or so, there's not much difference, IMO. And once the temperature is high in the cooler, it's slower to come down because of the insulation.
Everybody has their preferences. For my money, I'll replace the plastic bins once the seals go. I probably won't replace the coolers.
LeeBot wrote: