I've been looking into a case and will probably go with the Argon One which is both a massive heatsink and includes a configurable fan. I'll have to endure the fan for AV1 playback. Hopefully it won't be too annoying.
OTOH maybe the smarter alternative would be just to invest in a rpi5 instead of burning 25£ on an additional case.But when booting to LE isn't the bootloader firmware tied to the LE version? I'm not sure how to update it since that is the latest version shown to me.
I've had success with completely passive heatsink cases like the flirc one (which has a kodi branded variant).
There should be no tie between LE and bootloader. Latest bootloader will typically be fine for any images (even old ones).