Sidewinder SV2 vs Castle Sidewinder SCT vs HPI Flux Motive vs Duratrax Element etc

We have also been in our dispute about overheating components:
Some say this way: cooked in a closed condition, that ESC will overheat and burn up that there is no heat from the Component board.

My opinion and the other part of speakers that take the most rasprosanenny ESC - MMM V3-V5
BEC, Drivers, CPU gives off heat through the board to heat sinks a free stream air cools and board and all installed components.
From here our apanentam question?
as a closed case "in the air" environment in the stock cooled allegedly overheated in an epoxy resin or other details
If the thermal conductivity of air under the back cover ESC 0,026 [W / (m · K)]
thermal conductivity epoxy thermal conductivity of ~ 100 times higher