The "smart" features on it are genuinely useful for me - I have sleep apnea, as well as an eight sleep + the electronic platform. It automatically changes the elevation of my head based on apnea events, and I see a marked reduction in them when using this feature.
I have a cpap machine that also makes automatic adjustments but I still get noticeably better sleep quality with the eight sleep. I also really enjoy the temperature control, since it saves on HVAC costs vs. climate controlling the whole house. I've not tried an aquarium chiller for this purpose, though I have used one for doing temperature control on a beer fermenter, and I can extrapolate from there that I value the management of the actual eight sleep device vs. managing an aquarium chiller's temp control.