i like both the argon and the simple heatsink setups, either work great. i did end up adding an additional heatsink to the argon, the flat case does not provide great heat exchange in an enclosed space.
you can do passive cooling as well, just all depends on how hot the location gets.
should be fine, if you don’t like how warm it gets a set of small heatsinks for amplifiers will run you a few bucks and takes all of 10 seconds to install.