I’ve tried both. My passively cooled w/ small heat sink in a farly closed case Zero 2 in performace mode quickly reaches 60c for me and doesn’t exceed it. That’s sufficiently under the 80c at which it starts to throttle but warmer than I like. My 4b in an aluminum case with small heat sink and fan at full speed stays around 35c and doesn’t exceed 40c, numbers that I’m more comfortable with in a production environment. If I’m dealing with a few boxes a relatively poor MTBF is no big deal, but if I need to support a few humdred, geographically dispersed installations it’s a bigger deal. I think there are better cases for the Zero tha do a good job of heat dissipation. Meanwhile my fourth, and barely a month old pi 4b is losing one of it’s HDMI ports altogether, while the other is just flakey. I think those micro HDMI ports are its Achilles heel. If anyone has any ideas how to get those ports ready for production use I’d be grateful. It’s otherwise such a strong conteder.