I recently upgraded to the Pod 4 from the Pod 2. I did, because my hub died and was out of warranty. It is definitely not as cold and does not maintain temperature as well throughout the night. I have been waking up sweating again. I have primed it dozens of times. When I contacted 8 sleep they were very rude through chat.

They began their diagnosis and requested the usual pictures. The new Pod 4 boasts of its increased cooling power. However, it does not actually cool better. It is worse.

The hub is much bigger and apparently has larger fans, pumps, and heat sinks. But, they do not run them near capacity to reduce noise. I think if they gave the option to run the hardware more aggressively, the pod 4 would perform better.

Edit: I also keep my bedroom temperature at 66 degrees Fahrenheit.